Apparently, I cannot upload the patch here, so I just copy-pasted it below.
Subject: [PATCH] Optimized settings for txpower below 14dBm
---
.../stm32_radio_driver/radio_driver.c | 23 ++++++++++++++++++-
.../LoRaWAN/Mac/Region/RegionEU868.h | 2 +-
2 files changed, 23 insertions(+), 2 deletions(-)
diff --git a/Middlewares/Third_Party/SubGHz_Phy/stm32_radio_driver/radio_driver.c b/Middlewares/Third_Party/SubGHz_Phy/stm32_radio_driver/radio_driver.c
index d91579c..bea62ec 100644
--- a/Middlewares/Third_Party/SubGHz_Phy/stm32_radio_driver/radio_driver.c
+++ b/Middlewares/Third_Party/SubGHz_Phy/stm32_radio_driver/radio_driver.c
@@ -669,7 +669,27 @@ void SUBGRF_SetTxParams( uint8_t paSelect, int8_t power, RadioRampTimes_t rampTi
SUBGRF_WriteRegister( REG_TX_CLAMP, SUBGRF_ReadRegister( REG_TX_CLAMP ) | ( 0x0F << 1 ) );
// WORKAROUND END
- SUBGRF_SetPaConfig( 0x04, 0x07, 0x00, 0x01 );
+ int32_t TxConfig = RBI_GetTxConfig();
+ if (TxConfig == RBI_CONF_RFO_HP) {
+ // We are in rfo_hp ONLY but it's not optimal settings for other than +21dBm or +22dBm
+ // See Section 5.1.2 of Application Note
+ // https://www.st.com/resource/en/application_note/an5457-rf-matching-network-design-guide-for-stm32wl-series-stmicroelectronics.pdf
+
+ if (power <= 14) {
+ // compensate for power loss because of impedance mismatch
+ if (power > 10) {
+ power += 6;
+ SUBGRF_SetPaConfig(0x02, 0x03, 0x00, 0x01);
+ } else {
+ power += 4;
+ SUBGRF_SetPaConfig(0x02, 0x02, 0x00, 0x01);
+ }
+
+ }
+ } else {
+ SUBGRF_SetPaConfig(0x04, 0x07, 0x00, 0x01);
+ }
+
if( power > 22 )
{
power = 22;
diff --git a/Middlewares/Third_Party/LoRaWAN/Mac/Region/RegionEU868.h b/Middlewares/Third_Party/LoRaWAN/Mac/Region/RegionEU868.h
index f0efe44..749d3f1 100644
--- a/Middlewares/Third_Party/LoRaWAN/Mac/Region/RegionEU868.h
+++ b/Middlewares/Third_Party/LoRaWAN/Mac/Region/RegionEU868.h
@@ -122,7 +122,7 @@ extern "C"
/*!
* Default Max EIRP
*/
-#define EU868_DEFAULT_MAX_EIRP 16.0f
+#define EU868_DEFAULT_MAX_EIRP 16.2f
/*!
* Default antenna gain