diff --git a/firmware/src/leds.cpp b/firmware/src/leds.cpp
index 18f8ba1..563f466 100644
--- a/firmware/src/leds.cpp
+++ b/firmware/src/leds.cpp
@@ -12,6 +12,8 @@ uint pusher_sm = 255; // invalid
 uint delay_sm = 255; // invalid
 uint row_sm = 255; // invalid
 
+#define LEDS_PIO_CLKDIV 1
+
 // NOTE: RCLK, SRCLK capture on *rising* edge
 inline void pulsePin(uint8_t pin) {
   gpio_put(pin, HIGH);
@@ -36,7 +38,7 @@ inline void outputEnable(uint8_t pin, bool enable) {
 uint8_t brightnessPhase = 0;
 
 // delays in nanoseconds
-#define NS_TO_DELAY(ns) ns / NS_PER_CYCLE
+#define NS_TO_DELAY(ns) (ns / NS_PER_CYCLE / LEDS_PIO_CLKDIV)
 uint32_t brightnessPhaseDelays[COLOR_BITS] = {
   NS_TO_DELAY(50),
   NS_TO_DELAY(100),
@@ -104,18 +106,18 @@ void leds_set_framebuffer(uint8_t *buffer) {
         }
 
         // set row shifting data
-        bool firstRow = y == (ROW_COUNT - 1);
-        uint32_t rowPulses = 1;
+        bool firstRow = y == 0;
+        uint32_t extraPulses = 0;
 
         if (moduleY == 0) {
-          rowPulses++;
+          extraPulses++;
         }
 
         if (moduleY == 7 || moduleY == 14 || (moduleY == 0 && yModule != 0)) {
-          rowPulses++;
+          extraPulses++;
         }
 
-        uint32_t rowData = firstRow | (rowPulses << 1);
+        uint32_t rowData = firstRow | (extraPulses << 1);
         ledBuffer[bi][outputYOffset + COL_MODULES] = rowData;
       }
     }
@@ -224,7 +226,7 @@ void leds_initPusher() {
   uint offset = pio_add_program(pio, &leds_px_pusher_program);
 
   pio_sm_config config = leds_px_pusher_program_get_default_config(offset);
-  sm_config_set_clkdiv_int_frac(&config, 1, 0);
+  sm_config_set_clkdiv_int_frac(&config, LEDS_PIO_CLKDIV, 0);
 
   // Shift OSR to the right, autopull
   sm_config_set_out_shift(&config, true, true, 32);
@@ -264,7 +266,7 @@ void leds_initRowSelector() {
   uint offset = pio_add_program(pio, &leds_row_selector_program);
 
   pio_sm_config config = leds_row_selector_program_get_default_config(offset);
-  sm_config_set_clkdiv_int_frac(&config, 1, 0);
+  sm_config_set_clkdiv_int_frac(&config, LEDS_PIO_CLKDIV, 0);
 
   // Shift OSR to the right, autopull
   sm_config_set_out_shift(&config, true, true, 32);
@@ -293,7 +295,7 @@ void leds_initDelay() {
   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);
+  sm_config_set_clkdiv_int_frac(&config, LEDS_PIO_CLKDIV, 0);
 
   // Shift OSR to the right, autopull
   sm_config_set_out_shift(&config, true, true, 32);
diff --git a/firmware/src/leds.h b/firmware/src/leds.h
index c0d8510..80231f6 100644
--- a/firmware/src/leds.h
+++ b/firmware/src/leds.h
@@ -24,10 +24,10 @@
 
 #define COLOR_BITS 8
 #define FPS 30
-#define MS_PER_FRAME 1000 / FPS
+#define MS_PER_FRAME (1000 / FPS)
 
 #define CPU_MHZ 125
-#define NS_PER_CYCLE 1000 / CPU_MHZ
+#define NS_PER_CYCLE (1000 / CPU_MHZ)
 
 void leds_init();
 void leds_initRenderer();
diff --git a/firmware/src/leds.pio b/firmware/src/leds.pio
index 84dd463..cf559e7 100644
--- a/firmware/src/leds.pio
+++ b/firmware/src/leds.pio
@@ -1,6 +1,6 @@
 .define public irq_did_latch 0
-.define public irq_delaying 1
 .define public irq_row_selected 1
+.define public irq_delaying 2
 
 ; TODO: check if delays can be lowered with a PCB
 .define public srclk_0_delay 1
@@ -48,7 +48,7 @@ entry_point:
 .wrap_target
   ; LSB=1 indicates first (bottom) row, ergo, high SER for the first pulse
   out pins, 1                   side 0  [srclk_0_delay]
-  ; The rest of the word indicates number of SRCLK pulses
+  ; The rest of the word indicates number of extra SRCLK pulses
   out x, 31
 loop:
   ; pulse SRCLK x times
diff --git a/firmware/src/leds.pio.h b/firmware/src/leds.pio.h
index 70af97f..43cde1e 100644
--- a/firmware/src/leds.pio.h
+++ b/firmware/src/leds.pio.h
@@ -9,8 +9,8 @@
 #endif
 
 #define irq_did_latch 0
-#define irq_delaying 1
 #define irq_row_selected 1
+#define irq_delaying 2
 #define srclk_0_delay 1
 #define srclk_1_delay 2
 #define rclk_1_delay 3
@@ -29,7 +29,7 @@ static const uint16_t leds_px_pusher_program_instructions[] = {
     0x1a41, //  2: jmp    x--, 1          side 1 [2] 
     0x7028, //  3: out    x, 8            side 0     
     0x0020, //  4: jmp    !x, 0                      
-    0x2041, //  5: wait   0 irq, 1                   
+    0x2042, //  5: wait   0 irq, 2                   
     0x20c1, //  6: wait   1 irq, 1                   
     0xc000, //  7: irq    nowait 0                   
     0xe301, //  8: set    pins, 1                [3] 
@@ -98,10 +98,10 @@ static inline pio_sm_config leds_row_selector_program_get_default_config(uint of
 static const uint16_t leds_delay_program_instructions[] = {
             //     .wrap_target
     0x20c0, //  0: wait   1 irq, 0                   
-    0xc001, //  1: irq    nowait 1                   
+    0xc002, //  1: irq    nowait 2                   
     0x6020, //  2: out    x, 32                      
     0x1043, //  3: jmp    x--, 3          side 0     
-    0xd841, //  4: irq    clear 1         side 1     
+    0xd842, //  4: irq    clear 2         side 1     
             //     .wrap
 };