3 files changed, 15 insertions, 5 deletions

diff --git a/docs/serial_driver.md b/docs/serial_driver.md
index bc376b6dd..c98f4c117 100644
--- a/docs/serial_driver.md
+++ b/docs/serial_driver.md
@@ -60,6 +60,7 @@ Configure the hardware via your config.h:
                                    //  5: about 19200 baud
 #define SERIAL_USART_DRIVER SD1 // USART driver of TX pin. default: SD1
 #define SERIAL_USART_TX_PAL_MODE 7 // Pin "alternate function", see the respective datasheet for the appropriate values for your MCU. default: 7
+#define SERIAL_USART_TIMEOUT 100 // USART driver timeout. default 100
 ```
 
 You must also enable the ChibiOS `SERIAL` feature:
diff --git a/drivers/chibios/serial_usart.c b/drivers/chibios/serial_usart.c
index 62b4913cb..72fcaed0c 100644
--- a/drivers/chibios/serial_usart.c
+++ b/drivers/chibios/serial_usart.c
@@ -58,7 +58,10 @@
 #    error invalid SELECT_SOFT_SERIAL_SPEED value
 #endif
 
-#define TIMEOUT 100
+#ifndef SERIAL_USART_TIMEOUT
+#    define SERIAL_USART_TIMEOUT 100
+#endif
+
 #define HANDSHAKE_MAGIC 7
 
 static inline msg_t sdWriteHalfDuplex(SerialDriver* driver, uint8_t* data, uint8_t size) {
@@ -201,21 +204,21 @@ int soft_serial_transaction(int index) {
     sdClear(&SERIAL_USART_DRIVER);
 
     // First chunk is always transaction id
-    sdWriteTimeout(&SERIAL_USART_DRIVER, &sstd_index, sizeof(sstd_index), TIME_MS2I(TIMEOUT));
+    sdWriteTimeout(&SERIAL_USART_DRIVER, &sstd_index, sizeof(sstd_index), TIME_MS2I(SERIAL_USART_TIMEOUT));
 
     uint8_t sstd_index_shake = 0xFF;
 
     // Which we always read back first so that we can error out correctly
     //   - due to the half duplex limitations on return codes, we always have to read *something*
     //   - without the read, write only transactions *always* succeed, even during the boot process where the slave is not ready
-    res = sdReadTimeout(&SERIAL_USART_DRIVER, &sstd_index_shake, sizeof(sstd_index_shake), TIME_MS2I(TIMEOUT));
+    res = sdReadTimeout(&SERIAL_USART_DRIVER, &sstd_index_shake, sizeof(sstd_index_shake), TIME_MS2I(SERIAL_USART_TIMEOUT));
     if (res < 0 || (sstd_index_shake != (sstd_index ^ HANDSHAKE_MAGIC))) {
         dprintf("serial::usart_shake NO_RESPONSE\n");
         return TRANSACTION_NO_RESPONSE;
     }
 
     if (trans->initiator2target_buffer_size) {
-        res = sdWriteTimeout(&SERIAL_USART_DRIVER, trans->initiator2target_buffer, trans->initiator2target_buffer_size, TIME_MS2I(TIMEOUT));
+        res = sdWriteTimeout(&SERIAL_USART_DRIVER, trans->initiator2target_buffer, trans->initiator2target_buffer_size, TIME_MS2I(SERIAL_USART_TIMEOUT));
         if (res < 0) {
             dprintf("serial::usart_transmit NO_RESPONSE\n");
             return TRANSACTION_NO_RESPONSE;
@@ -223,7 +226,7 @@ int soft_serial_transaction(int index) {
     }
 
     if (trans->target2initiator_buffer_size) {
-        res = sdReadTimeout(&SERIAL_USART_DRIVER, trans->target2initiator_buffer, trans->target2initiator_buffer_size, TIME_MS2I(TIMEOUT));
+        res = sdReadTimeout(&SERIAL_USART_DRIVER, trans->target2initiator_buffer, trans->target2initiator_buffer_size, TIME_MS2I(SERIAL_USART_TIMEOUT));
         if (res < 0) {
             dprintf("serial::usart_receive NO_RESPONSE\n");
             return TRANSACTION_NO_RESPONSE;
diff --git a/readme.md b/readme.md
index 6092f209b..6321681a9 100644
--- a/readme.md
+++ b/readme.md
@@ -7,6 +7,12 @@
 [![GitHub contributors](https://img.shields.io/github/contributors/qmk/qmk_firmware.svg)](https://github.com/qmk/qmk_firmware/pulse/monthly)
 [![GitHub forks](https://img.shields.io/github/forks/qmk/qmk_firmware.svg?style=social&label=Fork)](https://github.com/qmk/qmk_firmware/)
 
+# THIS IS THE DEVELOP BRANCH
+
+Warning- This is the `develop` branch of QMK Firmware. You may encounter broken code here. Please see [Breaking Changes](https://docs.qmk.fm/#/breaking_changes) for more information.
+
+# Original readme continues
+
 This is a keyboard firmware based on the [tmk\_keyboard firmware](https://github.com/tmk/tmk_keyboard) with some useful features for Atmel AVR and ARM controllers, and more specifically, the [OLKB product line](https://olkb.com), the [ErgoDox EZ](https://ergodox-ez.com) keyboard, and the [Clueboard product line](https://clueboard.co).
 
 ## Documentation