sseg: add support for PWM per segment

src/main.c

@@ -132,6 +132,18 @@ static void update_countdown_fsm(uint32_t time_ms)
 				sseg_set_char(2, 'f', false);
 			}
 
+			{ // animation block
+				uint32_t modtime = time_in_state % 3000;
+
+				if(modtime < 500) {
+					sseg_set_pwm_percent(0, 100 - 75 * modtime / 500);
+				} else if(modtime < 1000) {
+					sseg_set_pwm_percent(1, 100 - 75 * (modtime - 500) / 500);
+				} else if(modtime < 1500) {
+					sseg_set_pwm_percent(2, 100 - 75 * (modtime - 1000) / 500);
+				}
+			}
+
 			if(buttons_get_events(BTN_ON) & BTN_EVENT_PRESSED) {
 				m_countdown_state = COUNTDOWN_STARTING;
 			}
@@ -148,6 +160,10 @@ static void update_countdown_fsm(uint32_t time_ms)
 					sseg_set_char(0, '|', false);
 					sseg_set_char(1, ' ', false);
 					sseg_set_char(2, ' ', false);
+
+					sseg_set_pwm_percent(0, 100);
+					sseg_set_pwm_percent(1, 100);
+					sseg_set_pwm_percent(2, 100);
 					break;
 
 				case 500:

src/sseg.c

@@ -23,10 +23,11 @@
 #define SSEG_START_PIN 0
 
 static volatile uint32_t m_dma_buffer[4] __attribute__((aligned(4*sizeof(uint32_t *)))) = {
-	0x0000013D, // segment 0 = 'Z' = '2'
+	//AABBDDCC; DD = segment code; CC = PWM off time; BB = multiplexer pins; AA = PWM on time
-	0x00000277, // segment 1 = A
+	0xFF013D00, // segment 0 = 'Z' = '2'
-	0x00000476, // segment 2 = M
+	0xFF027700, // segment 1 = A
-	0x00000000, // dummy entry
+	0xFF047600, // segment 2 = M
+	0x00000000, // dummy entry (all off, for the shortest possible time)
 };
 
 static PIO m_pio;
@@ -173,5 +174,15 @@ void sseg_loop(void)
 void sseg_set_char(uint8_t seg, char c, bool with_dot)
 {
 	uint dot_bit = with_dot ? 0x80 : 0x00;
-	m_dma_buffer[seg] = (m_dma_buffer[seg] & 0xFFFFFF00) | dot_bit | ascii_to_sseg(c);
+	m_dma_buffer[seg] = (m_dma_buffer[seg] & 0xFFFF00FF) | ((dot_bit | ascii_to_sseg(c)) << 8);
+}
+
+void sseg_set_pwm_times(uint8_t seg, uint8_t on_time, uint8_t off_time)
+{
+	m_dma_buffer[seg] = (m_dma_buffer[seg] & 0x00FFFF00) | ((uint32_t)on_time << 24) | (uint32_t)off_time;
+}
+
+void sseg_set_pwm_percent(uint8_t seg, uint8_t on_percent)
+{
+	sseg_set_pwm_times(seg, on_percent, 100-on_percent);
 }

src/sseg.h

@@ -9,4 +9,7 @@ void sseg_loop(void);
 
 void sseg_set_char(uint8_t seg, char c, bool with_dot);
 
+void sseg_set_pwm_times(uint8_t seg, uint8_t on_time, uint8_t off_time);
+void sseg_set_pwm_percent(uint8_t seg, uint8_t on_percent);
+
 #endif // SSEG_H

src/sseg.pio

@@ -3,8 +3,14 @@
 ; Repeatedly get one word of data from the TX FIFO, stalling when the FIFO is
 ; empty. Write the least significant bit to the OUT pin group.
 
-loop:
+next_digit:
     set pins, 0x00             ; set MUX pins to 0
     pull
-    out pins, 11        [31]   ; write the data from the FIFO to the outputs and wait some time
+    out x, 8                   ; load "pwm on" cycle count into the scratch register
-    jmp loop            [31]   ; repeat and wait some extra time
+off_loop:
+    jmp x--, off_loop
+    out pins, 16               ; set the segment pins (only the lower 11 bits are used)
+    out x, 8                   ; load "pwm on" cycle count into the scratch register
+on_loop:
+    jmp x--, on_loop
+    jmp next_digit             ; repeat the whole process