PXS20RM Datasheet, PDF (151/1368 Pages) Freescale Semiconductor, Inc – PXS20 Microcontroller

Boot Assist Module (BAM)
The LINFlex controller is configured to operate at a baud rate of f_XOSC / 833, using 8 bit data frame without
parity bit and 1 stop bit. For cut2/3, when autobaud feature is disabled, the system clock is driven by the
external oscillator. For cut1, the system clock is driven by the internal RC oscillator (16 MHz), resulting
in a baud rate of f_XOSC / 833 = 19200.
Table 8-4. LINFlex bit timing in UART mode
8.4.3.2 Protocol
Table 8-5 summarizes the protocol and BAM action during this boot mode.
Table 8-5. UART boot mode download protocol (autobaud disabled)
Protocol
step
Host sent message
BAM response
message
Action
1
64-bit password (MSB 64-bit password
Password checked for validity and compared against
first)
stored password.
2
32-bit store address 32-bit store address
Load address is stored for future use.
3
VLE bit +
VLE bit +
Size of download is stored for future use.
31-bit number of bytes 31-bit number of bytes
Verify VLE bit.
(MSB first)
(MSB first)
4
8 bits of raw
binarydata
8 bits of raw
binarydata
4 x 8 bits of data are packed into 32-bit words. These
words are saved into SRAM starting from the “Load
address”.
“Load address” increments until the number of data
received and stored matches the size as specified in the
previous step.
5
none
none
Branch to downloaded code
8.4.4 CAN Boot — autobaud disabled
8.4.4.1 Configuration
Boot using the CAN protocol is implemented by FlexCAN_0 module. Pins used are:
• CAN_TX corresponds to pin B[0]
• CAN_RX corresponds to pin B[1].
Boot from FlexCAN with autobaud disabled uses the system clock driven by the external oscillator.
The FlexCAN controller is configured to operate at a baud rate = system clock frequency/40.
PXS20 Microcontroller Reference Manual, Rev. 1
Freescale Semiconductor
8-9