From d957e276bd9c9b52175cce93636940262828021f Mon Sep 17 00:00:00 2001
From: Ashley Strahle <ash@jackofclubs.com.au>
Date: Tue, 23 Jun 2026 22:49:59 +0000
Subject: [PATCH] =?UTF-8?q?Fix=20daisy-chain=20MUX=20byte=20order:=20MUX1?=
 =?UTF-8?q?=20(first=208=20bits)=20=E2=86=92=20low=20byte/switches=200-7,?=
 =?UTF-8?q?=20MUX2=20=E2=86=92=20high=20byte/switches=208-15?=
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---
 src/pixel_stomp_mux.cpp | 34 ++++++++++++++++++++++++++--------
 1 file changed, 26 insertions(+), 8 deletions(-)

diff --git a/src/pixel_stomp_mux.cpp b/src/pixel_stomp_mux.cpp
index da98215..98e3fb0 100644
--- a/src/pixel_stomp_mux.cpp
+++ b/src/pixel_stomp_mux.cpp
@@ -37,15 +37,25 @@ uint16_t PixelStompMux::read_buttons() {
     digitalWrite(pin_ld, HIGH);
     delayMicroseconds(BMC_MUX_74HC165_DELAY);
 
-    uint16_t data = 0;
-    for (int i = 15; i >= 0; i--) {
-        bitWrite(data, i, digitalRead(pin_di));
+    uint8_t mux1 = 0;
+    for (int i = 7; i >= 0; i--) {
+        bitWrite(mux1, i, digitalRead(pin_di));
         digitalWrite(pin_clk, HIGH);
         delayMicroseconds(BMC_MUX_74HC165_DELAY);
         digitalWrite(pin_clk, LOW);
         delayMicroseconds(BMC_MUX_74HC165_DELAY);
     }
 
+    uint8_t mux2 = 0;
+    for (int i = 7; i >= 0; i--) {
+        bitWrite(mux2, i, digitalRead(pin_di));
+        digitalWrite(pin_clk, HIGH);
+        delayMicroseconds(BMC_MUX_74HC165_DELAY);
+        digitalWrite(pin_clk, LOW);
+        delayMicroseconds(BMC_MUX_74HC165_DELAY);
+    }
+
+    uint16_t data = ((uint16_t)mux2 << 8) | mux1;
     last_button_state = data;
     return data;
 }
@@ -104,16 +114,24 @@ void PixelStompMux::probe() {
         digitalWrite(pin_ld, HIGH);
         delayMicroseconds(BMC_MUX_74HC165_DELAY);
 
-        uint16_t data = 0;
-        for (int i = 15; i >= 0; i--) {
-            bool bit_val = digitalRead(pin_di);
-            bitWrite(data, i, bit_val);
+        uint8_t mux1 = 0;
+        uint8_t mux2 = 0;
+        for (int i = 7; i >= 0; i--) {
+            bitWrite(mux1, i, digitalRead(pin_di));
             digitalWrite(pin_clk, HIGH);
             delayMicroseconds(BMC_MUX_74HC165_DELAY);
             digitalWrite(pin_clk, LOW);
             delayMicroseconds(BMC_MUX_74HC165_DELAY);
         }
-        Serial.printf("  Round %d: 0x%04X\n", round, data);
+        for (int i = 7; i >= 0; i--) {
+            bitWrite(mux2, i, digitalRead(pin_di));
+            digitalWrite(pin_clk, HIGH);
+            delayMicroseconds(BMC_MUX_74HC165_DELAY);
+            digitalWrite(pin_clk, LOW);
+            delayMicroseconds(BMC_MUX_74HC165_DELAY);
+        }
+        uint16_t data = ((uint16_t)mux2 << 8) | mux1;
+        Serial.printf("  Round %d: 0x%04X (MUX1=0x%02X MUX2=0x%02X)\n", round, data, mux1, mux2);
 
         delay(500);
     }