card_emu: Ensure the length is properly set on a TPDU header rctx
diff --git a/firmware/src_simtrace/card_emu.c b/firmware/src_simtrace/card_emu.c
index 54805e3..97b3d94 100644
--- a/firmware/src_simtrace/card_emu.c
+++ b/firmware/src_simtrace/card_emu.c
@@ -506,7 +506,7 @@
cardemu_hdr_set(&rd->hdr, CEMU_USB_MSGT_DO_RX_DATA);
rd->flags = CEMU_DATA_F_TPDU_HDR;
rctx->tot_len = sizeof(*rd) + sizeof(ch->tpdu.hdr);
- rctx->idx = 0;
+ rctx->idx = sizeof(ch->tpdu.hdr);
/* copy TPDU header to data field */
memcpy(rd->data, ch->tpdu.hdr, sizeof(ch->tpdu.hdr));