From 3261c04afbdcc7ccfde40591b514d8f438837cff Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Thomas=20G=C3=B6ttgens?= <tgoettgens@gmail.com>
Date: Mon, 18 May 2026 11:18:40 +0200
Subject: [PATCH] Fix Antenna Switch on Cardputer (#10491)

---
 .../m5stack_cardputer_adv/variant.cpp         | 49 +++++++++++++++++++
 1 file changed, 49 insertions(+)

diff --git a/src/platform/extra_variants/m5stack_cardputer_adv/variant.cpp b/src/platform/extra_variants/m5stack_cardputer_adv/variant.cpp
index 7ec9dca80..0c252159f 100644
--- a/src/platform/extra_variants/m5stack_cardputer_adv/variant.cpp
+++ b/src/platform/extra_variants/m5stack_cardputer_adv/variant.cpp
@@ -3,14 +3,63 @@
 #ifdef M5STACK_CARDPUTER_ADV
 
 #include "AudioBoard.h"
+#include <Wire.h>
 
 DriverPins PinsAudioBoardES8311;
 AudioBoard board(AudioDriverES8311, PinsAudioBoardES8311);
 
+// PI4IOE5V6408 on the optional Cap LoRa-1262 (and Cap LoRa868).
+#define PI4IO_ADDR 0x43
+#define PI4IO_REG_IO_DIR 0x03
+#define PI4IO_REG_OUT_SET 0x05
+#define PI4IO_REG_OUT_H_IM 0x07
+
+static TwoWire *findLoraCapBus()
+{
+    TwoWire *candidates[] = {&Wire1, &Wire};
+    for (size_t i = 0; i < sizeof(candidates) / sizeof(candidates[0]); ++i) {
+        candidates[i]->beginTransmission(PI4IO_ADDR);
+        if (candidates[i]->endTransmission() == 0) {
+            return candidates[i];
+        }
+    }
+    return nullptr;
+}
+
+static bool pi4ioWrite(TwoWire *bus, uint8_t reg, uint8_t val)
+{
+    bus->beginTransmission(PI4IO_ADDR);
+    bus->write(reg);
+    bus->write(val);
+    uint8_t status = bus->endTransmission();
+    if (status != 0) {
+        LOG_DEBUG("PI4IO write reg=0x%02x val=0x%02x failed, I2C status=%u", reg, val, status);
+        return false;
+    }
+    return true;
+}
+
+static void initLoraCap()
+{
+    TwoWire *bus = findLoraCapBus();
+    if (!bus) {
+        LOG_ERROR("Cap LoRa-1262 not found");
+        return;
+    }
+    bool ok = pi4ioWrite(bus, PI4IO_REG_IO_DIR, 0b00000001);
+    ok = ok && pi4ioWrite(bus, PI4IO_REG_OUT_H_IM, 0b00000001);
+    ok = ok && pi4ioWrite(bus, PI4IO_REG_OUT_SET, 0b00000001);
+    if (!ok) {
+        LOG_ERROR("Antenna switch init failed");
+    }
+}
+
 // M5stack Cardputer ADV specific init
 
 void lateInitVariant()
 {
+    initLoraCap();
+
     // AudioDriverLogger.begin(Serial, AudioDriverLogLevel::Debug);
     //  I2C: function, scl, sda
     PinsAudioBoardES8311.addI2C(PinFunction::CODEC, Wire);