From 3c1a0941aa56cc733cacb385d7784cafb78f736e Mon Sep 17 00:00:00 2001 From: Ryan Gregg Date: Fri, 20 Mar 2026 17:56:04 -0700 Subject: [PATCH] Fix POE boot failure on RAK4631 Ethernet builds MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Drive WB_IO2 (slot power switch) HIGH via early constructor before the Arduino framework initializes. Without this, the board brownouts on POE-only power because the slot MOSFET isn't enabled early enough for the RAK13800 POE module to deliver power to the baseboard. Also remove the W5100S hardware reset pulse from Ethernet init — the chip comes out of power-on reset cleanly, and toggling reset kills the PHY link which breaks POE power delivery. --- src/helpers/nrf52/EthernetCLI.h | 10 ++++------ src/helpers/nrf52/SerialEthernetInterface.cpp | 17 +++++------------ variants/rak4631/RAK4631Board.cpp | 13 +++++++++++++ 3 files changed, 22 insertions(+), 18 deletions(-) diff --git a/src/helpers/nrf52/EthernetCLI.h b/src/helpers/nrf52/EthernetCLI.h index 6a59bda6..9ccc34f4 100644 --- a/src/helpers/nrf52/EthernetCLI.h +++ b/src/helpers/nrf52/EthernetCLI.h @@ -36,13 +36,11 @@ static void ethernet_task(void* param) { (void)param; Serial.println("ETH: Initializing hardware"); - pinMode(PIN_ETHERNET_POWER_EN, OUTPUT); - digitalWrite(PIN_ETHERNET_POWER_EN, HIGH); - vTaskDelay(pdMS_TO_TICKS(100)); - + // WB_IO2 (power enable) is already driven HIGH by early constructor + // in RAK4631Board.cpp to support POE boot. + // Skip hardware reset — the W5100S comes out of power-on reset cleanly, + // and toggling reset kills the PHY link which breaks POE power. pinMode(PIN_ETHERNET_RESET, OUTPUT); - digitalWrite(PIN_ETHERNET_RESET, LOW); - vTaskDelay(pdMS_TO_TICKS(100)); digitalWrite(PIN_ETHERNET_RESET, HIGH); ETHERNET_SPI_PORT.begin(); diff --git a/src/helpers/nrf52/SerialEthernetInterface.cpp b/src/helpers/nrf52/SerialEthernetInterface.cpp index 92001b1b..4288c0f7 100644 --- a/src/helpers/nrf52/SerialEthernetInterface.cpp +++ b/src/helpers/nrf52/SerialEthernetInterface.cpp @@ -22,20 +22,13 @@ bool SerialEthernetInterface::begin() { ETHERNET_DEBUG_PRINTLN("Ethernet initializing"); -#ifdef PIN_ETHERNET_POWER_EN - ETHERNET_DEBUG_PRINTLN("Ethernet power enable"); - pinMode(PIN_ETHERNET_POWER_EN, OUTPUT); - digitalWrite(PIN_ETHERNET_POWER_EN, HIGH); // Power up. - delay(100); - ETHERNET_DEBUG_PRINTLN("Ethernet power enabled"); -#endif - + // WB_IO2 (power enable) is already driven HIGH by early constructor + // in RAK4631Board.cpp to support POE boot. + // Skip hardware reset — the W5100S comes out of power-on reset cleanly, + // and toggling reset kills the PHY link which breaks POE power. #ifdef PIN_ETHERNET_RESET pinMode(PIN_ETHERNET_RESET, OUTPUT); - digitalWrite(PIN_ETHERNET_RESET, LOW); // Reset Time. - delay(100); - digitalWrite(PIN_ETHERNET_RESET, HIGH); // Reset Time. - ETHERNET_DEBUG_PRINTLN("Ethernet reset pulse"); + digitalWrite(PIN_ETHERNET_RESET, HIGH); #endif uint8_t mac[6]; diff --git a/variants/rak4631/RAK4631Board.cpp b/variants/rak4631/RAK4631Board.cpp index 08286604..1b5698d0 100644 --- a/variants/rak4631/RAK4631Board.cpp +++ b/variants/rak4631/RAK4631Board.cpp @@ -1,8 +1,21 @@ #include #include +#include "nrf_gpio.h" #include "RAK4631Board.h" +#ifdef ETHERNET_ENABLED +// Drive WB_IO2 HIGH as early as possible using direct register access. +// WB_IO2 (P1.02, Arduino pin 34) controls the WisBlock slot power switch. +// With POE through RAK13800, this must be enabled before the framework +// initializes or the board will brownout from insufficient power delivery. +// Priority 102 runs just after SystemInit. +static void __attribute__((constructor(102))) rak4631_early_poe_power() { + nrf_gpio_cfg_output(NRF_GPIO_PIN_MAP(1, 2)); // WB_IO2 = P1.02 + nrf_gpio_pin_set(NRF_GPIO_PIN_MAP(1, 2)); +} +#endif + #ifdef NRF52_POWER_MANAGEMENT // Static configuration for power management // Values set in variant.h defines