Specifications

MCU slave software
Developer’s Serial Bootloader, Rev. 13
Freescale Semiconductor 47
Figure 30. Software-SCI receive char routine
ENTER
RXD PIN IS
INITIALIZE AND FEED
16-BIT TIMER
SET BIT COUNTER
TO 9
SHIFT-IN RECEIVE
CHAR AND CLEAR MSB
SET MSB
DECREMENT
BITS AND TEST?
SET
CLEAR
STOP TIMER
EXIT
WITH 1.5 BIT TIME
RUN TIMER
FEED 16-BIT TIMER
WITH 1 BIT TIME
WAIT FOR
TIMER FLAG
TIMER FLAG
RECEIVED?
NO
YES
WAIT FOR
RXD LOW
RXD LOW
?
NO
YES
SET OR CLEAR?
CLEAR TIMER FLAG
= 0
