wait for TXREADY to avoid serial transmit buffer overrun

2012-10-27 10:29:37 +00:00
parent 9c20f60004
commit 254317c13b
2 changed files with 16 additions and 3 deletions
--- a/sources/printf_helper.S
+++ b/sources/printf_helper.S
@@ -3,6 +3,10 @@
 			.global printf_helper
 printf_helper:
 			.extern		__MBAR
-			lea			__MBAR+0x860C,a0
-			move.b		d0,(a0)
+.wait_txready:
+			move.w		__MBAR+0x8604,d2	// PSCSCR0 status register
+			btst		#10,d2				// space left in TX fifo?
+			beq.s		.wait_txready		// no, loop
+			lea			__MBAR+0x860C,a0	// PSCSTB0 transmitter buffer register
+			move.b		d0,(a0)				// send byte
 			rts