Boot Assist Module (BAM)
MPC5566 Microcontroller Reference Manual, Rev. 2
Freescale Semiconductor 16-13
• Rx error counter errors
All data received, regardless of errors, is echoed out on the CNTXA signal.
NOTE
The host computer must compare the ‘echoed data’ to the sent data and
restart the process if an error is detected.
Refer to Figure 16-5 for details of FlexCAN bit timing.
Figure 16-5. FlexCAN Bit Timing
The eSCI is configured for one start bit, eight data bits, no parity and one stop bit and to operate at a baud
rate equal to the system clock divided by 1250. Refer to Table 16-9 for examples of baud rates.
The BAM ignores the following eSCI errors:
• Overrun errors
• Noise errors
• Framing errors
• Parity errors
All data received is assumed to be good and is echoed out on the TXD signal. It is the responsibility of the
host computer to compare the echoes with the sent data and restart the process if an error is detected.
Table 16-8. Serial Boot Mode—Baud Rate and Watchdog Summary
Crystal Frequency
(MHz)
System Clock
Frequency (MHz)
SCI Baud Rate
FlexCAN
Baud Rate
Watchdog Timeout
Period (seconds)
f
ref_crystal
f
sys
= 1.5 x f
ref_crystal
f
sys
÷ 1250 f
sys
÷ 60 (2.5 x 2
27
) ÷ f
sys
8 12 9600 200 K 28.0
SYNC_SEG Time segment 1 Time segment 2
Sample point
NRZ signal
Transmit point
1
time quanta time quanta time quanta
9 2
1 bit time
1 time quanta = 5 system clock periods = 3 1/3 crystal clock periods (with PLL enabled)
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