From 978548e74975647981ac4317e8144e2f57dbbc5f Mon Sep 17 00:00:00 2001
From: Tobias Gunkel <hennymcc@yahoo.de>
Date: Mon, 11 Mar 2024 02:38:21 +0100
Subject: [PATCH 1/2] Do not set LFCLKSRC as it will hang if no external
 crystal is present

---
 src/nrf_to_nrf.cpp | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/nrf_to_nrf.cpp b/src/nrf_to_nrf.cpp
index d9ce0b3..d074625 100644
--- a/src/nrf_to_nrf.cpp
+++ b/src/nrf_to_nrf.cpp
@@ -90,10 +90,10 @@ bool nrf_to_nrf::begin()
         // Do nothing.
     }
 
-    NRF_CLOCK->LFCLKSRC = (CLOCK_LFCLKSRC_SRC_Xtal << CLOCK_LFCLKSRC_SRC_Pos);
     NRF_CLOCK->EVENTS_LFCLKSTARTED = 0;
     NRF_CLOCK->TASKS_LFCLKSTART = 1;
 
+    /* Wait for the low frequency clock to start up */
     while (NRF_CLOCK->EVENTS_LFCLKSTARTED == 0) {
         // Do nothing.
     }

From 95126e2b9e7ecc2bdc5341ad15bb1f59f68c8bfa Mon Sep 17 00:00:00 2001
From: Tobias Gunkel <hennymcc@yahoo.de>
Date: Mon, 11 Mar 2024 02:36:24 +0100
Subject: [PATCH 2/2] Add support for 250kbps mode

---
 src/nrf_to_nrf.cpp | 20 ++++++++++++++++----
 src/nrf_to_nrf.h   |  2 ++
 2 files changed, 18 insertions(+), 4 deletions(-)

diff --git a/src/nrf_to_nrf.cpp b/src/nrf_to_nrf.cpp
index d9ce0b3..a2767d6 100644
--- a/src/nrf_to_nrf.cpp
+++ b/src/nrf_to_nrf.cpp
@@ -2,6 +2,12 @@
 
 #include "nrf_to_nrf.h"
 
+// Note that 250Kbit mode is deprecated and might not work reliably on all devices.
+// See: https://devzone.nordicsemi.com/f/nordic-q-a/78469/250-kbit-s-nordic-proprietary-radio-mode-on-nrf52840
+#ifndef RADIO_MODE_MODE_Nrf_250Kbit
+#define RADIO_MODE_MODE_Nrf_250Kbit (2UL)
+#endif
+
 /**********************************************************************************************************/
 
 // Function to do bytewise bit-swap on an unsigned 32-bit value
@@ -448,8 +454,9 @@ bool nrf_to_nrf::write(void* buf, uint8_t len, bool multicast, bool doEncryption
             if (!DPL) {
                 if (NRF_RADIO->MODE == (RADIO_MODE_MODE_Nrf_1Mbit << RADIO_MODE_MODE_Pos)) {
                     realAckTimeout -= ACK_TIMEOUT_1MBPS_OFFSET;
-                }
-                else {
+                } else if (NRF_RADIO->MODE == (RADIO_MODE_MODE_Nrf_250Kbit << RADIO_MODE_MODE_Pos)) {
+                    realAckTimeout -= ACK_TIMEOUT_250KBPS_OFFSET;
+                } else {
                     realAckTimeout -= ACK_TIMEOUT_2MBPS_OFFSET;
                 }
             }else{
@@ -1032,14 +1039,19 @@ bool nrf_to_nrf::isChipConnected() { return isValid(); }
 bool nrf_to_nrf::setDataRate(uint8_t speed)
 {
 
-    if (!speed) {
+    if (speed == NRF_1MBPS) {
         NRF_RADIO->MODE = (RADIO_MODE_MODE_Nrf_1Mbit << RADIO_MODE_MODE_Pos);
         ackTimeout = ACK_TIMEOUT_1MBPS;
     }
-    else {
+    else if (speed == NRF_250KBPS) {
+        NRF_RADIO->MODE = (RADIO_MODE_MODE_Nrf_250Kbit << RADIO_MODE_MODE_Pos);
+        ackTimeout = ACK_TIMEOUT_250KBPS;
+    }
+    else { // NRF_2MBPS
         NRF_RADIO->MODE = (RADIO_MODE_MODE_Nrf_2Mbit << RADIO_MODE_MODE_Pos);
         ackTimeout = ACK_TIMEOUT_2MBPS;
     }
+
     return 1;
 }
 
diff --git a/src/nrf_to_nrf.h b/src/nrf_to_nrf.h
index ab00abe..1edcffa 100644
--- a/src/nrf_to_nrf.h
+++ b/src/nrf_to_nrf.h
@@ -17,8 +17,10 @@
 #define ACTUAL_MAX_PAYLOAD_SIZE  127
 #define ACK_TIMEOUT_1MBPS        500 // 200 with static payloads
 #define ACK_TIMEOUT_2MBPS        300 // 165 with static payloads
+#define ACK_TIMEOUT_250KBPS      500
 #define ACK_TIMEOUT_1MBPS_OFFSET 300
 #define ACK_TIMEOUT_2MBPS_OFFSET 135
+#define ACK_TIMEOUT_250KBPS_OFFSET 300
 #define ACK_PAYLOAD_TIMEOUT_OFFSET 750
 
 // AES CCM ENCRYPTION