From 3ef784b83027beb22779375f730d188407859dc7 Mon Sep 17 00:00:00 2001
From: Martin Ling <martin-git@earth.li>
Date: Fri, 6 Feb 2026 17:59:25 +0000
Subject: [PATCH] Add delay loop implementation for M0 core.

---
 firmware/common/delay.c | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/firmware/common/delay.c b/firmware/common/delay.c
index 8d2045ed..ceb7693e 100644
--- a/firmware/common/delay.c
+++ b/firmware/common/delay.c
@@ -32,6 +32,7 @@ void delay(uint32_t duration)
 
 void delay_us_at_mhz(uint32_t us, uint32_t mhz)
 {
+#if defined(LPC43XX_M4)
 	// The loop below takes 3 cycles per iteration.
 	uint32_t loop_iterations = (us * mhz) / 3;
 	asm volatile("start%=:\n"
@@ -39,4 +40,15 @@ void delay_us_at_mhz(uint32_t us, uint32_t mhz)
 		     "    bpl start%=\n"            // 2 cycles
 		     :
 		     : [ITERATIONS] "r"(loop_iterations));
+#elif defined(LPC43XX_M0)
+	// The loop below takes 4 cycles per iteration.
+	uint32_t loop_iterations = (us * mhz) / 4;
+	asm volatile("start%=:\n"
+		     "    sub %[ITERATIONS], #1\n" // 1 cycle
+		     "    bpl start%=\n"           // 3 cycles
+		     :
+		     : [ITERATIONS] "r"(loop_iterations));
+#else
+	#error "No delay loop implementation"
+#endif
 }