MC68HC908LB8_05 データシートの表示（PDF） - Freescale Semiconductor

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MC68HC908LB8_05

On-Chip FLASH Programming Routines

Freescale Semiconductor 

Example 2: Sending a Byte Serially

Example 2 shows how to send a byte ($55) serially on PTA0:

PutByte equ $0381

bclr 0,DDRA

bclr 0,PTA

lda #$55

jsr PutByte

;LB8 PutByte jump address

;Configure port A bit 0 as an input

;Initialize data bit to zero PTA0=0

;Load sent data $55 to A

;Call PutByte routine

How to Use the Routines

RDVRRNG

When using the RDVRRNG routine, the user must select one of the following function options:

• Send-out option — Used to read a range of FLASH locations and to send the read data to a host

through PTA0 by using the PutByte routine.

• Verify option — Used to read a range of FLASH locations and to verify the read data against the

DATA array.

Send-Out Option

If the accumulator (A) is initialized with $00 at the routine entry, the read data will be sent out serially

through PTA0. The communication baud rate is the same as the baud rate described in the PutByte

routine. When this option is selected, the PTA0 must be pulled up and configured as an input and the

PTA0 data bit must be initialized to 0.

Verify Option

If A is initialized with a non-zero value, the read data is verified against the DATA array for each byte of

FLASH and the DATA array is replaced by the data read from FLASH. If the data does not match the

corresponding value, the data read from FLASH can be confirmed in the DATA array. All data in the DATA

array must be in the zero page, but a range can be beyond a row size or a page size.

Carry (C) Bit and Checksum

The first and last addresses of the range to be read and/or verified are specified as parameters in

registers H:X and LADDR, respectively. In the verify option, the carry (C) bit of the condition code register

(CCR) is set if the data in the specified range is verified successfully against the data in the DATA array.

However when the send-out option is selected, the status of the C bit is meaningless because this

function does not include the verify operation. Both options calculate a checksum on data read in the

range. This checksum, which is the LSB of the sum of all bytes in the entire data collection, is stored in A

upon return from the function.

Interrupts are not masked. The COP is serviced in RDVRRNG. The first COP is serviced at 23 bus cycles

after this routine is called in the user software. However, the COP timeout might still occur in the send-out

option if the COP is configured for a short timeout period.

On-Chip FLASH Programming Routines, Rev. 4

Freescale Semiconductor

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