PXS20RM Datasheet, PDF (152/1368 Pages) Freescale Semiconductor, Inc – PXS20 Microcontroller

Boot Assist Module (BAM)
It uses the standard 11 bit identifier format detailed in FlexCAN 2.0A specification.
FlexCAN controller bit timing is programmed with 10 time quanta, and the sample point is 2 time quanta
before the end, as shown in Figure 8-5.
NRZ Signal
SYNC_SEG
Time Segment 1
Time Segment 2
1
time quantum
7
time quanta
1 Bit Time
Transmit Point
1 time Quantum = 4 system clock periods
Figure 8-5. FlexCAN bit timing
2
time quanta
Sample Point
8.4.4.2 Protocol
Table 8-6 summarizes the protocol and BAM action during this boot mode. All data is transmitted byte
wise.
Table 8-6. FlexCAN boot mode download protocol (autobaud disabled).
Protoco
l step
Host sent
message
BAM response
message
Action
1 FlexCAN ID 0x011+ FlexCAN ID 0x001+ Password checked for validity and compared against stored
64-bit password 64-bit password
password.
2 FlexCAN ID 0x012+ FlexCAN ID 0x002+
32-bit store
32-bit store
address+
address+
VLE bit+
VLE bit+
31-bit number of 31-bit number of
bytes
bytes
Load address is stored for future use.
Size of download are stored for future use.
Verify VLE bit.
3 FlexCAN ID 0x013+ FlexCAN ID 0x003+ 4 x 8 bits of data are packed into 32-bit words. These words are
8 to 64 bits of raw 8 to 64 bits of raw
saved into SRAM starting from the “Load address”.
binary data
binary data
“Load address” increments until the number of data received
and stored matches the size as specified in the previous step.
4 none
none
Branch to downloaded code
8-10
PXS20 Microcontroller Reference Manual, Rev. 1
Freescale Semiconductor