v1.7.0v1.7.0

- Added TX “start delay” compensation for timestamp mode (fix time window alignment issue at low SF and/or high BW)
- Added adaptive narrowband/wideband TX filtering for LoRa
- Added a command-line option to set CR in util_tx_test
- Added notes for TX “start delay” in immediate and triggered mode

/!\ warning: due to start delay compensation being implemented, TX that were
previously 1.5ms late will be sent on time. At low datarate, this is not an
issue. At high LoRa data rate (and FSK) you might have to adjust your timing.

1 files changed, 22 insertions, 10 deletions

diff --git a/libloragw/src/loragw_hal.c b/libloragw/src/loragw_hal.c
index 96ab391..5dbdf45 100644
--- a/libloragw/src/loragw_hal.c
+++ b/libloragw/src/loragw_hal.c
@@ -1252,7 +1252,7 @@ int lgw_start(void) {
 	wait_ms(1);
 	
 	lgw_reg_r(LGW_MCU_AGC_STATUS, &read_val);
-	if (read_val != 0x20) {
+	if (read_val != 0x10) {
 		DEBUG_PRINTF("ERROR: AGC FIRMWARE INITIALIZATION FAILURE, STATUS 0x%02X\n", (uint8_t)read_val);
 		return LGW_HAL_ERROR;
 	}
@@ -1287,6 +1287,12 @@ int lgw_start(void) {
 		}
 	#endif
 	
+	/* Load Tx freq MSBs (always 3 if f > 768 for SX1257 or f > 384 for SX1255 */
+	lgw_reg_w(LGW_RADIO_SELECT, AGC_CMD_WAIT);
+	wait_ms(1);
+	lgw_reg_w(LGW_RADIO_SELECT, 3);
+	wait_ms(1);
+	
 	/* Load chan_select firmware option */
 	lgw_reg_w(LGW_RADIO_SELECT, AGC_CMD_WAIT);
 	wait_ms(1);
@@ -1552,6 +1558,7 @@ int lgw_send(struct lgw_pkt_tx_s pkt_data) {
 	int payload_offset = 0; /* start of the payload content in the databuffer */
 	uint8_t pow_index = 0; /* 4-bit value to set the firmware TX power */
 	uint8_t target_mix_gain = 0; /* used to select the proper I/Q offset correction */
+	uint32_t count_trig; /* timestamp value in trigger mode corrected for TX start delay */
 	
 	/* check if the concentrator is running */
 	if (lgw_is_started == false) {
@@ -1657,10 +1664,15 @@ int lgw_send(struct lgw_pkt_tx_s pkt_data) {
 	buff[2] = 0xFF & part_frac; /* Least Significant Byte */
 	
 	/* metadata 3 to 6, timestamp trigger value */
-	buff[3] = 0xFF & (pkt_data.count_us >> 24);
-	buff[4] = 0xFF & (pkt_data.count_us >> 16);
-	buff[5] = 0xFF & (pkt_data.count_us >> 8);
-	buff[6] = 0xFF &  pkt_data.count_us;
+	/* TX state machine must be triggered at T0 - TX_START_DELAY for packet to start being emitted at T0 */
+	if (pkt_data.tx_mode == TIMESTAMPED)
+	{
+		count_trig = pkt_data.count_us - TX_START_DELAY;
+		buff[3] = 0xFF & (count_trig >> 24);
+		buff[4] = 0xFF & (count_trig >> 16);
+		buff[5] = 0xFF & (count_trig >> 8);
+		buff[6] = 0xFF &  count_trig;
+	}
 	
 	/* parameters depending on modulation  */
 	if (pkt_data.modulation == MOD_LORA) {
@@ -1726,11 +1738,11 @@ int lgw_send(struct lgw_pkt_tx_s pkt_data) {
 		buff[14] = 0;
 		buff[15] = 0;
 		
-		/* LSB of RF frequency is now used in AGC firmware to implement large/narrow filtering in SX1257/55 */
+		/* MSB of RF frequency is now used in AGC firmware to implement large/narrow filtering in SX1257/55 */
 		if (pkt_data.bandwidth == BW_500KHZ) {
-			buff[2] |= 0x01; /* Enlarge filter for 500kHz BW */
+			buff[0] |= 0x80; /* Enlarge filter for 500kHz BW */
 		} else {
-			buff[2] &= 0xFE;
+			buff[0] &= 0x7F;
 		}
 		
 	} else if (pkt_data.modulation == MOD_FSK) {
@@ -1769,8 +1781,8 @@ int lgw_send(struct lgw_pkt_tx_s pkt_data) {
 		++transfer_size; /* one more byte to transfer to the TX modem */
 		++payload_offset; /* start the payload with one more byte of offset */
 		
-		/* LSB of RF frequency is now used in AGC firmware to implement large/narrow filtering in SX1257/55*/
-		buff[2] &= 0xFE; /* Always use narrow band for FSK (force LSB to 0) */
+		/* MSB of RF frequency is now used in AGC firmware to implement large/narrow filtering in SX1257/55 */
+		buff[0] &= 0x7F; /* Always use narrow band for FSK (force MSB to 0) */
 		
 	} else {
 		DEBUG_MSG("ERROR: INVALID TX MODULATION..\n");