CYRF69103
Document #: 001-07611 Rev *B
Page 17 of 73
a halt, to force the program to jump directly into the setup code
and not run into it.
halt
SSCOP: mov [KEY1], 3ah
mov X, SP
mov A, X
add A, 3
mov [KEY2], A
The SROM also features Return Codes and Lockouts.
Return Codes
Return codes aid in the determination of success or failure of
a particular function. The return code is stored in KEY1’s
position in the parameter block. The CheckSum and
TableRead functions do not have return codes because
KEY1’s position in the parameter block is used to return other
data.
Read, write, and erase operations may fail if the target block
is read or write protected. Block protection levels are set
during device programming.
The EraseAll function overwrites data in addition to leaving the
entire user Flash in the erase state. The EraseAll function
loops through the number of Flash macros in the product,
executing the following sequence: erase, bulk program all
zeros, erase. After all the user space in all the Flash macros
are erased, a second loop erases and then programs each
protection block with zeros.
SROM Function Descriptions
All SROM functions are described in the following sections.
SWBootReset Function
The SROM function, SWBootReset, is the function that is
responsible for transitioning the device from a reset state to
running user code. The SWBootReset function is executed
whenever the SROM is entered with an M8C accumulator
value of 00h; the SRAM parameter block is not used as an
input to the function. This will happen, by design, after a
hardware reset, because the M8C's accumulator is reset to
00h or when user code executes the SSC instruction with an
accumulator value of 00h. The SWBootReset function will not
execute when the SSC instruction is executed with a bad key
value and a nonzero function code. A CYRF69103 device will
execute the HALT instruction if a bad value is given for either
KEY1 or KEY2.
The SWBootReset function verifies the integrity of the
calibration data by way of a 16-bit checksum, before releasing
the M8C to run user code.
ReadBlock Function
The ReadBlock function is used to read 64 contiguous bytes
from Flash—a block.
The first thing this function does is to check the protection bits
and determine if the desired BLOCKID is readable. If read
protection is turned on, the ReadBlock function will exit setting
the accumulator and KEY2 back to 00h. KEY1 will have a
value of 01h, indicating a read failure. If read protection is not
enabled, the function will read 64 bytes from the Flash using
a ROMX instruction and store the results in SRAM using an
MVI instruction. The first of the 64 bytes will be stored in SRAM
at the address indicated by the value of the POINTER
parameter. When the ReadBlock completes successfully, the
accumulator, KEY1 and KEY2, will all have a value of 00h.
WriteBlock Function
The WriteBlock function is used to store data in the Flash. Data
is moved 64 bytes at a time from SRAM to Flash using this
function. The first thing the WriteBlock function does is to
check the protection bits and determine if the desired
BLOCKID is writable. If write protection is turned on, the Write-
Block function will exit, setting the accumulator and KEY2 back
to 00h. KEY1 will have a value of 01h, indicating a write failure.
The configuration of the WriteBlock function is straightforward.
The BLOCKID of the Flash block, where the data is stored,
must be determined and stored at SRAM address FAh.
The SRAM address of the first of the 64 bytes to be stored in
Flash must be indicated using the POINTER variable in the
parameter block (SRAM address FBh). Finally, the CLOCK
and DELAY values must be set correctly. The CLOCK value
Table 21.SROM Function Parameters
Variable Name
SRAM Address
Key1/Counter/Return Code
0,F8h
Key2/TMP
0,F9h
BlockID
0,FAh
Pointer
0,FBh
Clock
0,FCh
Mode
0,FDh
Delay
0,FEh
PCL
0,FFh
Table 22.SROM Return Codes
Return Code
Description
00h
Success
01h
Function not allowed due to level of protection
on block
02h
Software reset without hardware reset
03h
Fatal error, SROM halted
Table 23.ReadBlock Parameters
Name
Address
Description
KEY1
0,F8h
3Ah
KEY2
0,F9h
Stack Pointer value, when SSC is
executed
BLOCKID
0,FAh
Flash block number
POINTER
0,FBh
First of 64 addresses in SRAM
where returned data should be
stored
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