don't call fronthaul write on RX in TDD.

targets/RT/USER/lte-ru.c

@@ -312,7 +312,8 @@ static inline void fh_if5_mobipass_south_out(RU_t *ru) {
 static inline void fh_if4p5_south_out(RU_t *ru) {
   if (ru == RC.ru[0]) VCD_SIGNAL_DUMPER_DUMP_VARIABLE_BY_NAME( VCD_SIGNAL_DUMPER_VARIABLES_TRX_TST, ru->proc.timestamp_tx&0xffffffff );
   LOG_D(PHY,"Sending IF4p5 for frame %d subframe %d\n",ru->proc.frame_tx,ru->proc.subframe_tx);
-  send_IF4p5(ru,ru->proc.frame_tx, ru->proc.subframe_tx, IF4p5_PDLFFT);
+  if (subframe_select(&ru->frame_parms,ru->proc.subframe_tx)!=SF_UL) 
+    send_IF4p5(ru,ru->proc.frame_tx, ru->proc.subframe_tx, IF4p5_PDLFFT);
 }
 
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