wip: pio-based delay

firmware/src/leds.cpp

@@ -7,8 +7,9 @@
 #include "leds.h"
 #include "leds.pio.h"
 
-PIO pusher_pio = pio0;
+PIO leds_pio = pio0;
 uint pusher_sm = 255; // invalid
+uint delay_sm = 255; // invalid
 
 // NOTE: RCLK, SRCLK capture on *rising* edge
 inline void pulsePin(uint8_t pin) {
@@ -89,6 +90,7 @@ void leds_initPusher();
 
 void leds_initRenderer() {
   leds_initPusher();
+  leds_initDelay();
   multicore_reset_core1();
   multicore_launch_core1(main2);
 }
@@ -143,14 +145,14 @@ void leds_render() {
       // - DMA?
       for (int xModule = 0; xModule < COL_MODULES; xModule++) {
         uint32_t pxValues = buffer[bufferOffset + xModule];
-        pio_sm_put_blocking(pusher_pio, pusher_sm, pxValues);
+        pio_sm_put_blocking(leds_pio, pusher_sm, pxValues);
       }
 
       // wait until pushing and RCLK latch are done
-      while (!pio_interrupt_get(pusher_pio, 0)) {
+      while (!pio_interrupt_get(leds_pio, 0)) {
         tight_loop_contents();
       }
-      pio_interrupt_clear(pusher_pio, pusher_sm);
+      pio_interrupt_clear(leds_pio, pusher_sm);
 
       // show for a certain period
       outputEnable(ROW_OE, true);
@@ -167,7 +169,7 @@ void leds_render() {
 }
 
 void leds_initPusher() {
-  PIO pio = pusher_pio;
+  PIO pio = leds_pio;
   uint sm = pio_claim_unused_sm(pio, true);
   pusher_sm = sm;
 
@@ -204,3 +206,26 @@ void leds_initPusher() {
   pio_sm_init(pio, sm, offset, &config);
   pio_sm_set_enabled(pio, sm, true);
 }
+
+void leds_initDelay() {
+  PIO pio = leds_pio;
+  uint sm = pio_claim_unused_sm(pio, true);
+  delay_sm = sm;
+
+  uint offset = pio_add_program(pio, &leds_delay_program);
+
+  pio_sm_config config = leds_delay_program_get_default_config(offset);
+  sm_config_set_clkdiv_int_frac(&config, 1, 0);
+
+  // Shift OSR to the right, autopull
+  sm_config_set_out_shift(&config, true, true, 32);
+
+  // Set sideset (OE) pin, connect to pad, set as output
+  sm_config_set_sideset_pins(&config, ROW_OE);
+  pio_gpio_init(pio, ROW_OE);
+  pio_sm_set_consecutive_pindirs(pio, sm, ROW_OE, 1, true);
+
+  // Load our configuration, and jump to the start of the program
+  pio_sm_init(pio, sm, offset, &config);
+  pio_sm_set_enabled(pio, sm, true);
+}

firmware/src/leds.pio

@@ -1,3 +1,6 @@
+.define public irq_did_latch 0
+.define public irq_delaying 1
+
 .program leds_px_pusher
 .side_set 1 opt
 public entry_point:
@@ -22,10 +25,32 @@ end:
   jmp x-- end_of_row
   .wrap
 end_of_row:
-  ; indicate to main processor that row was processed
-  irq set 0
+  ; wait until previous row's delay is complete
+  wait 0 irq irq_delaying
+  ; signal that row is processed
+  irq set irq_did_latch
   ; clock RCLK (latch onto register output stage)
   set pins, 1 [3]
   set pins, 0
   ; wait for next row
   jmp entry_point
+
+.program leds_delay
+.side_set 1 opt
+.define public output_on 0
+.define public output_off 1
+public entry_point:
+  ; begin only after data is latched
+  wait 1 irq irq_did_latch
+  ; signal that delay is ongoing
+  irq set irq_delaying
+  ; x = number of cycles to delay
+  out x, 32
+loop:
+  ; busy loop for x cycles
+  ; enable output
+  jmp x-- loop                  side output_on
+end:
+  ; signal that delay is complete
+  ; disable output
+  irq clear irq_delaying        side output_off

firmware/src/leds.pio.h

@@ -8,6 +8,9 @@
 #include "hardware/pio.h"
 #endif
 
+#define irq_did_latch 0
+#define irq_delaying 1
+
 // -------------- //
 // leds_px_pusher //
 // -------------- //
@@ -25,16 +28,17 @@ static const uint16_t leds_px_pusher_program_instructions[] = {
     0x7028, //  3: out    x, 8            side 0     
     0x0045, //  4: jmp    x--, 5                     
             //     .wrap
-    0xc000, //  5: irq    nowait 0                   
-    0xe301, //  6: set    pins, 1                [3] 
-    0xe000, //  7: set    pins, 0                    
-    0x0000, //  8: jmp    0                          
+    0x2041, //  5: wait   0 irq, 1                   
+    0xc000, //  6: irq    nowait 0                   
+    0xe301, //  7: set    pins, 1                [3] 
+    0xe000, //  8: set    pins, 0                    
+    0x0000, //  9: jmp    0                          
 };
 
 #if !PICO_NO_HARDWARE
 static const struct pio_program leds_px_pusher_program = {
     .instructions = leds_px_pusher_program_instructions,
-    .length = 9,
+    .length = 10,
     .origin = -1,
 };
 
@@ -46,3 +50,40 @@ static inline pio_sm_config leds_px_pusher_program_get_default_config(uint offse
 }
 #endif
 
+// ---------- //
+// leds_delay //
+// ---------- //
+
+#define leds_delay_wrap_target 0
+#define leds_delay_wrap 4
+
+#define leds_delay_output_on 0
+#define leds_delay_output_off 1
+
+#define leds_delay_offset_entry_point 0u
+
+static const uint16_t leds_delay_program_instructions[] = {
+            //     .wrap_target
+    0x20c0, //  0: wait   1 irq, 0                   
+    0xc001, //  1: irq    nowait 1                   
+    0x6020, //  2: out    x, 32                      
+    0x1043, //  3: jmp    x--, 3          side 0     
+    0xd841, //  4: irq    clear 1         side 1     
+            //     .wrap
+};
+
+#if !PICO_NO_HARDWARE
+static const struct pio_program leds_delay_program = {
+    .instructions = leds_delay_program_instructions,
+    .length = 5,
+    .origin = -1,
+};
+
+static inline pio_sm_config leds_delay_program_get_default_config(uint offset) {
+    pio_sm_config c = pio_get_default_sm_config();
+    sm_config_set_wrap(&c, offset + leds_delay_wrap_target, offset + leds_delay_wrap);
+    sm_config_set_sideset(&c, 2, true, false);
+    return c;
+}
+#endif
+