From 81358aa7b3dcfdb7b6054fb161e09fca68ea45d7 Mon Sep 17 00:00:00 2001
From: Thijs Havinga <94684410+HavingaThijs@users.noreply.github.com>
Date: Wed, 6 Nov 2024 14:41:37 +0100
Subject: [PATCH] cpu/cc2538: use RX FIFO count to determine CRC OK location

---
 cpu/cc2538/radio/cc2538_rf_radio_ops.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/cpu/cc2538/radio/cc2538_rf_radio_ops.c b/cpu/cc2538/radio/cc2538_rf_radio_ops.c
index 9640f68bcd..31e80be022 100644
--- a/cpu/cc2538/radio/cc2538_rf_radio_ops.c
+++ b/cpu/cc2538/radio/cc2538_rf_radio_ops.c
@@ -412,9 +412,9 @@ void cc2538_irq_handler(void)
 
     if (flags_f0 & RXPKTDONE) {
         handled_f0 |= RXPKTDONE;
-        /* CRC check */
-        uint8_t pkt_len = rfcore_peek_rx_fifo(0);
-        if (rfcore_peek_rx_fifo(pkt_len) & CC2538_CRC_BIT_MASK) {
+        /* CRC_OK bit is in the last byte in the RX FIFO */
+        uint8_t crc_loc = RFCORE_XREG_RXFIFOCNT - 1;
+        if (rfcore_peek_rx_fifo(crc_loc) & CC2538_CRC_BIT_MASK) {
             /* Disable RX while the frame has not been processed */
             _disable_rx();
             /* If AUTOACK is disabled or the ACK request bit is not set */