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453 lines
14 KiB
453 lines
14 KiB
#include "onewire.h"
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#include "string.h"
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#include "task.h"
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#include <driver/gpio.h>
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#define ONEWIRE_SELECT_ROM 0x55
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#define ONEWIRE_SKIP_ROM 0xcc
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#define ONEWIRE_SEARCH 0xf0
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// Waits up to `max_wait` microseconds for the specified pin to go high.
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// Returns true if successful, false if the bus never comes high (likely
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// shorted).
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static inline bool _onewire_wait_for_bus(int pin, int max_wait) {
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bool state;
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for (int i = 0; i < ((max_wait + 4) / 5); i++) {
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if (gpio_get_level(pin)) break;
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os_delay_us(5);
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}
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state = gpio_get_level(pin);
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// Wait an extra 1us to make sure the devices have an adequate recovery
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// time before we drive things low again.
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os_delay_us(1);
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return state;
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}
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// Perform the onewire reset function. We will wait up to 250uS for
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// the bus to come high, if it doesn't then it is broken or shorted
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// and we return false;
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//
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// Returns true if a device asserted a presence pulse, false otherwise.
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//
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bool onewire_reset(int pin) {
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bool r;
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gpio_set_direction(pin, GPIO_MODE_OUTPUT_OD);
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gpio_set_level(pin, 1);
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// wait until the wire is high... just in case
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if (!_onewire_wait_for_bus(pin, 250)) return false;
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gpio_set_level(pin, 0);
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os_delay_us(480);
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taskENTER_CRITICAL();
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gpio_set_level(pin, 1); // allow it to float
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os_delay_us(70);
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r = !gpio_get_level(pin);
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taskEXIT_CRITICAL();
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// Wait for all devices to finish pulling the bus low before returning
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if (!_onewire_wait_for_bus(pin, 410)) return false;
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return r;
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}
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static bool _onewire_write_bit(int pin, bool v) {
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if (!_onewire_wait_for_bus(pin, 10)) return false;
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if (v) {
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taskENTER_CRITICAL();
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gpio_set_level(pin, 0); // drive output low
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os_delay_us(10);
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gpio_set_level(pin, 1); // allow output high
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taskEXIT_CRITICAL();
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os_delay_us(55);
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} else {
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taskENTER_CRITICAL();
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gpio_set_level(pin, 0); // drive output low
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os_delay_us(65);
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gpio_set_level(pin, 1); // allow output high
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taskEXIT_CRITICAL();
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}
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os_delay_us(1);
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return true;
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}
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static int _onewire_read_bit(int pin) {
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int r;
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if (!_onewire_wait_for_bus(pin, 10)) return -1;
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taskENTER_CRITICAL();
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gpio_set_level(pin, 0);
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os_delay_us(2);
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gpio_set_level(pin, 1); // let pin float, pull up will raise
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os_delay_us(11);
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r = gpio_get_level(pin); // Must sample within 15us of start
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taskEXIT_CRITICAL();
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os_delay_us(48);
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return r;
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}
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// Write a byte. The writing code uses open-drain mode and expects the pullup
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// resistor to pull the line high when not driven low. If you need strong
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// power after the write (e.g. DS18B20 in parasite power mode) then call
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// onewire_power() after this is complete to actively drive the line high.
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//
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bool onewire_write(int pin, uint8_t v) {
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uint8_t bitMask;
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for (bitMask = 0x01; bitMask; bitMask <<= 1) {
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if (!_onewire_write_bit(pin, (bitMask & v))) {
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return false;
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}
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}
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return true;
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}
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bool onewire_write_bytes(int pin, const uint8_t *buf, size_t count) {
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size_t i;
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for (i = 0; i < count; i++) {
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if (!onewire_write(pin, buf[i])) {
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return false;
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}
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}
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return true;
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}
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// Read a byte
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//
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int onewire_read(int pin) {
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uint8_t bitMask;
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int r = 0;
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int bit;
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for (bitMask = 0x01; bitMask; bitMask <<= 1) {
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bit = _onewire_read_bit(pin);
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if (bit < 0) {
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return -1;
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} else if (bit) {
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r |= bitMask;
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}
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}
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return r;
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}
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bool onewire_read_bytes(int pin, uint8_t *buf, size_t count) {
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size_t i;
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int b;
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for (i = 0; i < count; i++) {
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b = onewire_read(pin);
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if (b < 0) return false;
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buf[i] = b;
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}
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return true;
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}
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bool onewire_select(int pin, onewire_addr_t addr) {
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uint8_t i;
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if (!onewire_write(pin, ONEWIRE_SELECT_ROM)) {
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return false;
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}
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for (i = 0; i < 8; i++) {
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if (!onewire_write(pin, addr & 0xff)) {
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return false;
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}
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addr >>= 8;
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}
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return true;
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}
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bool onewire_skip_rom(int pin) {
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return onewire_write(pin, ONEWIRE_SKIP_ROM);
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}
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bool onewire_power(int pin) {
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// Make sure the bus is not being held low before driving it high, or we
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// may end up shorting ourselves out.
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if (!_onewire_wait_for_bus(pin, 10)) return false;
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gpio_set_direction(pin, GPIO_MODE_OUTPUT);
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gpio_set_level(pin, 1);
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return true;
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}
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void onewire_depower(int pin) {
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gpio_set_direction(pin, GPIO_MODE_OUTPUT_OD);
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}
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void onewire_search_start(onewire_search_t *search) {
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// reset the search state
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memset(search, 0, sizeof(*search));
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}
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void onewire_search_prefix(onewire_search_t *search, uint8_t family_code) {
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uint8_t i;
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search->rom_no[0] = family_code;
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for (i = 1; i < 8; i++) {
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search->rom_no[i] = 0;
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}
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search->last_discrepancy = 64;
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search->last_device_found = false;
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}
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// Perform a search. If the next device has been successfully enumerated, its
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// ROM address will be returned. If there are no devices, no further
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// devices, or something horrible happens in the middle of the
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// enumeration then ONEWIRE_NONE is returned. Use OneWire::reset_search() to
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// start over.
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//
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// --- Replaced by the one from the Dallas Semiconductor web site ---
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//--------------------------------------------------------------------------
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// Perform the 1-Wire Search Algorithm on the 1-Wire bus using the existing
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// search state.
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// Return 1 : device found, ROM number in ROM_NO buffer
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// 0 : device not found, end of search
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//
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onewire_addr_t onewire_search_next(onewire_search_t *search, int pin) {
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//TODO: add more checking for read/write errors
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uint8_t id_bit_number;
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uint8_t last_zero, search_result;
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int rom_byte_number;
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int8_t id_bit, cmp_id_bit;
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onewire_addr_t addr;
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unsigned char rom_byte_mask;
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bool search_direction;
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// initialize for search
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id_bit_number = 1;
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last_zero = 0;
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rom_byte_number = 0;
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rom_byte_mask = 1;
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search_result = 0;
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// if the last call was not the last one
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if (!search->last_device_found) {
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// 1-Wire reset
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if (!onewire_reset(pin)) {
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// reset the search
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search->last_discrepancy = 0;
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search->last_device_found = false;
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return ONEWIRE_NONE;
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}
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// issue the search command
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onewire_write(pin, ONEWIRE_SEARCH);
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// loop to do the search
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do {
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// read a bit and its complement
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id_bit = _onewire_read_bit(pin);
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cmp_id_bit = _onewire_read_bit(pin);
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// check for no devices on 1-wire
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if ((id_bit < 0) || (cmp_id_bit < 0)) {
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// Read error
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break;
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} else if ((id_bit == 1) && (cmp_id_bit == 1)) {
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break;
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} else {
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// all devices coupled have 0 or 1
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if (id_bit != cmp_id_bit) {
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search_direction = id_bit; // bit write value for search
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} else {
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// if this discrepancy if before the Last Discrepancy
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// on a previous next then pick the same as last time
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if (id_bit_number < search->last_discrepancy) {
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search_direction = ((search->rom_no[rom_byte_number] & rom_byte_mask) > 0);
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} else {
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// if equal to last pick 1, if not then pick 0
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search_direction = (id_bit_number == search->last_discrepancy);
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}
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// if 0 was picked then record its position in LastZero
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if (!search_direction) {
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last_zero = id_bit_number;
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}
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}
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// set or clear the bit in the ROM byte rom_byte_number
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// with mask rom_byte_mask
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if (search_direction) {
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search->rom_no[rom_byte_number] |= rom_byte_mask;
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} else {
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search->rom_no[rom_byte_number] &= ~rom_byte_mask;
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}
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// serial number search direction write bit
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_onewire_write_bit(pin, search_direction);
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// increment the byte counter id_bit_number
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// and shift the mask rom_byte_mask
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id_bit_number++;
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rom_byte_mask <<= 1;
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// if the mask is 0 then go to new SerialNum byte rom_byte_number and reset mask
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if (rom_byte_mask == 0) {
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rom_byte_number++;
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rom_byte_mask = 1;
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}
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}
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} while (rom_byte_number < 8); // loop until through all ROM bytes 0-7
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// if the search was successful then
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if (!(id_bit_number < 65)) {
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// search successful so set last_discrepancy,last_device_found,search_result
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search->last_discrepancy = last_zero;
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// check for last device
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if (search->last_discrepancy == 0) {
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search->last_device_found = true;
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}
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search_result = 1;
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}
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}
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// if no device found then reset counters so next 'search' will be like a first
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if (!search_result || !search->rom_no[0]) {
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search->last_discrepancy = 0;
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search->last_device_found = false;
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return ONEWIRE_NONE;
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} else {
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addr = 0;
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for (rom_byte_number = 7; rom_byte_number >= 0; rom_byte_number--) {
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addr = (addr << 8) | search->rom_no[rom_byte_number];
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}
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//printf("Ok I found something at %08x%08x...\n", (uint32_t)(addr >> 32), (uint32_t)addr);
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}
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return addr;
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}
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// The 1-Wire CRC scheme is described in Maxim Application Note 27:
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// "Understanding and Using Cyclic Redundancy Checks with Maxim iButton Products"
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//
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#if ONEWIRE_CRC8_TABLE
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// This table comes from Dallas sample code where it is freely reusable,
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// though Copyright (C) 2000 Dallas Semiconductor Corporation
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static const uint8_t dscrc_table[] = {
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0, 94,188,226, 97, 63,221,131,194,156,126, 32,163,253, 31, 65,
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157,195, 33,127,252,162, 64, 30, 95, 1,227,189, 62, 96,130,220,
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35,125,159,193, 66, 28,254,160,225,191, 93, 3,128,222, 60, 98,
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190,224, 2, 92,223,129, 99, 61,124, 34,192,158, 29, 67,161,255,
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70, 24,250,164, 39,121,155,197,132,218, 56,102,229,187, 89, 7,
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219,133,103, 57,186,228, 6, 88, 25, 71,165,251,120, 38,196,154,
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101, 59,217,135, 4, 90,184,230,167,249, 27, 69,198,152,122, 36,
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248,166, 68, 26,153,199, 37,123, 58,100,134,216, 91, 5,231,185,
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140,210, 48,110,237,179, 81, 15, 78, 16,242,172, 47,113,147,205,
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17, 79,173,243,112, 46,204,146,211,141,111, 49,178,236, 14, 80,
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175,241, 19, 77,206,144,114, 44,109, 51,209,143, 12, 82,176,238,
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50,108,142,208, 83, 13,239,177,240,174, 76, 18,145,207, 45,115,
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202,148,118, 40,171,245, 23, 73, 8, 86,180,234,105, 55,213,139,
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87, 9,235,181, 54,104,138,212,149,203, 41,119,244,170, 72, 22,
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233,183, 85, 11,136,214, 52,106, 43,117,151,201, 74, 20,246,168,
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116, 42,200,150, 21, 75,169,247,182,232, 10, 84,215,137,107, 53};
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#ifndef pgm_read_byte
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#define pgm_read_byte(addr) (*(const uint8_t *)(addr))
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#endif
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//
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// Compute a Dallas Semiconductor 8 bit CRC. These show up in the ROM
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// and the registers. (note: this might better be done without to
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// table, it would probably be smaller and certainly fast enough
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// compared to all those delayMicrosecond() calls. But I got
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// confused, so I use this table from the examples.)
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//
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uint8_t onewire_crc8(const uint8_t *data, uint8_t len) {
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uint8_t crc = 0;
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while (len--) {
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crc = pgm_read_byte(dscrc_table + (crc ^ *data++));
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}
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return crc;
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}
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#else
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//
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// Compute a Dallas Semiconductor 8 bit CRC directly.
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// this is much slower, but much smaller, than the lookup table.
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//
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uint8_t onewire_crc8(const uint8_t *data, uint8_t len) {
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uint8_t crc = 0;
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while (len--) {
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uint8_t inbyte = *data++;
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for (int i = 8; i; i--) {
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uint8_t mix = (crc ^ inbyte) & 0x01;
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crc >>= 1;
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if (mix) crc ^= 0x8C;
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inbyte >>= 1;
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}
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}
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return crc;
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}
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#endif
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// Compute the 1-Wire CRC16 and compare it against the received CRC.
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// Example usage (reading a DS2408):
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// // Put everything in a buffer so we can compute the CRC easily.
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// uint8_t buf[13];
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// buf[0] = 0xF0; // Read PIO Registers
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// buf[1] = 0x88; // LSB address
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// buf[2] = 0x00; // MSB address
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// WriteBytes(net, buf, 3); // Write 3 cmd bytes
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// ReadBytes(net, buf+3, 10); // Read 6 data bytes, 2 0xFF, 2 CRC16
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// if (!CheckCRC16(buf, 11, &buf[11])) {
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// // Handle error.
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// }
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//
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// @param input - Array of bytes to checksum.
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// @param len - How many bytes to use.
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// @param inverted_crc - The two CRC16 bytes in the received data.
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// This should just point into the received data,
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// *not* at a 16-bit integer.
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// @param crc - The crc starting value (optional)
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// @return 1, iff the CRC matches.
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bool onewire_check_crc16(const uint8_t* input, size_t len, const uint8_t* inverted_crc, uint16_t crc_iv) {
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uint16_t crc = ~onewire_crc16(input, len, crc_iv);
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return (crc & 0xFF) == inverted_crc[0] && (crc >> 8) == inverted_crc[1];
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}
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// Compute a Dallas Semiconductor 16 bit CRC. This is required to check
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// the integrity of data received from many 1-Wire devices. Note that the
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// CRC computed here is *not* what you'll get from the 1-Wire network,
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// for two reasons:
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// 1) The CRC is transmitted bitwise inverted.
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// 2) Depending on the endian-ness of your processor, the binary
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// representation of the two-byte return value may have a different
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// byte order than the two bytes you get from 1-Wire.
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// @param input - Array of bytes to checksum.
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// @param len - How many bytes to use.
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// @param crc - The crc starting value (optional)
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// @return The CRC16, as defined by Dallas Semiconductor.
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uint16_t onewire_crc16(const uint8_t* input, size_t len, uint16_t crc_iv) {
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uint16_t crc = crc_iv;
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static const uint8_t oddparity[16] =
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{ 0, 1, 1, 0, 1, 0, 0, 1, 1, 0, 0, 1, 0, 1, 1, 0 };
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uint16_t i;
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for (i = 0; i < len; i++) {
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// Even though we're just copying a byte from the input,
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// we'll be doing 16-bit computation with it.
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uint16_t cdata = input[i];
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cdata = (cdata ^ crc) & 0xff;
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crc >>= 8;
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if (oddparity[cdata & 0x0F] ^ oddparity[cdata >> 4])
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crc ^= 0xC001;
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cdata <<= 6;
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crc ^= cdata;
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cdata <<= 1;
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crc ^= cdata;
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}
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return crc;
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}
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