AN2295 Freescale Semiconductor / Motorola, AN2295 Datasheet - Page 33

• Manufacturer Part Number: AN2295
• Description: Developers Serial Bootloader for M68HC08 and HCS08 MCUs
• Manufacturer: Freescale Semiconductor / Motorola

Software-SCI Receive Char Routine
The software-SCI receive routine is similar to software-SCI transmit. When the 16-bit output-compare
event is polled, the value of the receive pin is scanned. No provisions are made for stop-bit checking,
framing check, noise detection, etc., mainly because of memory restrictions.
software-SCI receive routine flowchart, and the source code is provided in
Freescale Semiconductor
INITIALIZE AND FEED
SET BIT COUNTER
WITH 1.5 BIT TIME
Developer’s Serial Bootloader for M68HC08 and HCS08 MCUs, Rev. 6
16-BIT TIMER
RUN TIMER
WAIT FOR
RXD LOW
RXD LOW
ENTER
TO 9
?
Figure 22. Software-SCI Receive Char Routine
YES
NO
CHAR AND CLEAR MSB
CLEAR TIMER FLAG
FEED 16-BIT TIMER
SHIFT-IN RECEIVE
BITS AND TEST?
SET OR CLEAR?
WITH 1 BIT TIME
DECREMENT
STOP TIMER
TIMER FLAG
TIMER FLAG
RECEIVED?
RXD PIN IS
WAIT FOR
EXIT
CLEAR
YES
= 0
SET
≠ 0
NO
SET MSB
Figure
Figure 22
23.
MCU Slave Software
shows the
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