update docs to indicate that SIPO works also for 595

examples/sipo_pwm_74xx4094_595/sipo_pwm_config.h

@@ -1,10 +1,17 @@
 /* Config for SIPO PWM */
 
-// PWM pin aliases
+// --- PWM pin aliases ---
+
+// Store signal
 #define SPWM_STR  D2
+// Shift/clock signal
 #define SPWM_CLK  D3
+// Data signal
 #define SPWM_DATA D4
 
+
+// --- Other settings ---
+
 // Number of PWM levels (color depth)
 #define SPWM_COLOR_DEPTH 256
 

lib/sipo_pwm.h

@@ -2,23 +2,28 @@
 
 // --- SIPO PWM Module ---
 //
-// SIPO = Serial IN, Parallel OUT
+// SIPO = shift register with paralel output.
 //
 // This module lets you use SIPO outputs as a "software PWM".
 //
-// Tested on 74HC4094,
+// Tested to work on 74hc4094 and 74hc595
-// should also work on 74HC595 (may need some small changes)
 
 #include <stdint.h>
 
 // Your file with configs
 #include "sipo_pwm_config.h"
 /*
-	// PWM pin aliases
+	// --- PWM pin aliases ---
+	
+	// Store signal
 	#define SPWM_STR  D2
+	// Shift/clock signal
 	#define SPWM_CLK  D3
+	// Data signal
 	#define SPWM_DATA D4
 	
+	// --- Other settings ---
+	
 	// Number of PWM levels (color depth)
 	#define SPWM_COLOR_DEPTH 256
 	
@@ -38,7 +43,7 @@ extern uint8_t spwm_levels[SPWM_CHANNELS];
 void spwm_init();
 
 
-/** Display PWM channels.
+/** Perform one PWM cycle.
- * This could be called in a Timer ISR.
+ * This should be called in a Timer ISR or a loop.
  */
 void spwm_send();