diff --git a/flake.nix b/flake.nix
index 015bec0..4afc50f 100644
--- a/flake.nix
+++ b/flake.nix
@@ -304,6 +304,7 @@
 
           pbuildInputs = [
             (packages."x86_64-linux"."dio" { inherit gcc cflags; })
+            pkgs.pkgsCross.avr.buildPackages.simavr
           ];
         };
 
diff --git a/tron-bag/main.c b/tron-bag/main.c
index 14acafc..55b10ab 100644
--- a/tron-bag/main.c
+++ b/tron-bag/main.c
@@ -3,58 +3,62 @@
 #include <dio.h>
 
 /*
-const struct avr_mmcu_vcd_trace_t _mytrace[]  _MMCU_ = {
+#include <simavr/avr/avr_mcu_section.h>
+AVR_MCU(F_CPU, "attiny85");
+
+const struct avr_mmcu_vcd_trace_t _mytrace[] _MMCU_ = {
+	{ AVR_MCU_VCD_SYMBOL("GTCCR"), .what = (void *)&GTCCR, },
+	{ AVR_MCU_VCD_SYMBOL("TCCR0A"), .what = (void *)&TCCR0A, },
+	{ AVR_MCU_VCD_SYMBOL("TCCR0B"), .what = (void *)&TCCR0B, },
 	{ AVR_MCU_VCD_SYMBOL("PORTB"), .what = (void *)&PORTB, },
+	{ AVR_MCU_VCD_SYMBOL("TCNT0"), .what = (void *)&TCNT0, },
 };
 */
 
-#define FPS                 100
+#define FPS                 10
 #define FPS_MS              1000 / FPS
 #define MULT                5
 
+/*
 typedef struct {
     uint8_t value;
     int8_t inc;
 } counter_t;
 
-void step_counter(counter_t *counter) {
-    int16_t value = counter->value;
-    value += counter->inc;
+void counter_update(counter_t *self) {
+    int16_t value = self->value;
+    value += self->inc;
 
     if (value >= 255) {
-        counter->value = 255;
-        counter->inc = -1;
+        self->value = 255;
+        self->inc = -1;
     } else if (value <= 0) {
-        counter->value = 0;
-        counter->inc = 1;
+        self->value = 0;
+        self->inc = 1;
     } else {
-        counter->value = value;
+        self->value = value;
     }
 }
+*/
 
 int main(void) {
-    dio_t dio0 = (dio_t){ .ddr = &DDRB, .port = &PORTB, .pin = &PINB, .addr = 0 };
-    dio_t dio1 = (dio_t){ .ddr = &DDRB, .port = &PORTB, .pin = &PINB, .addr = 1 };
-    dio_set_direction(&dio0, LINE_OUT);
-    dio_set_direction(&dio1, LINE_OUT);
+    DDRB = 0xff;
+    PORTB = 0;
 
-    // GTCCR = _BV(TSM) | _BV(PSR0);
-    TCCR0A = _BV(COM0A1) | _BV(COM0A0) | _BV(COM0B1) | _BV(COM0B0) | _BV(WGM01) | _BV(WGM00);
-    TCCR0B = _BV(WGM02) | _BV(CS00);
+    TCCR0A = _BV(COM0A1) | _BV(COM0B1) | _BV(WGM01) | _BV(WGM00);
+    TCCR0B = _BV(CS00);
 
-    counter_t red  = (counter_t){ .value = 128, .inc = -1 };
-    counter_t blue  = (counter_t){ .value = 128, .inc = -1 };
+    uint8_t brightness = 1;
 
-    // GTCCR &= ~_BV(TSM);
+    GTCCR = 0;
 
     while(1) {
-        step_counter(&red);
-        step_counter(&blue);
+        OCR0A = brightness;
+        OCR0B = brightness;
 
-        OCR0A = red.value;
-        OCR0B = blue.value;
+        _delay_ms(100);
 
-        _delay_ms(FPS_MS);
+        brightness += 1;
     }
 
     return 0;