© Koninklijke Philips Electronics N.V. 2006. All rights reserved.
User manual
Rev. 01 — 12 January 2006
235
Philips Semiconductors
UM10161
Volume 1
Chapter 19: Flash memory
19.7 Code Read Protection (CRP)
Code read protection is enabled by programming the flash address location 0x1FC (User
flash sector 0) with value 0x8765 4321 (2271560481 Decimal). Address 0x1FC is used to
allow some room for the FIQ exception handler. When the code read protection is enabled
the JTAG debug port, external memory boot and the following ISP commands are
disabled:
•
Read Memory
•
Write to RAM
•
Go
•
Copy RAM to Flash
The ISP commands mentioned above terminate with return code
CODE_READ_PROTECTION_ENABLED. The ISP erase command only allows erasure
of all user sectors when the code read protection is enabled. This limitation does not exist
if the code read protection is not enabled. IAP commands are not affected by the code
read protection.
Important: CRP is active/inactive once the device has gone through a power cycle.
19.8 ISP commands
The following commands are accepted by the ISP command handler. Detailed status
codes are supported for each command. The command handler sends the return code
INVALID_COMMAND when an undefined command is received. Commands and return
codes are in ASCII format.
CMD_SUCCESS is sent by ISP command handler only when received ISP command has
been completely executed and the new ISP command can be given by the host.
Exceptions from this rule are "Set Baud Rate", "Write to RAM", "Read Memory", and "Go"
commands.
Table 209: ISP command summary
ISP Command
Usage
Described in
Unlock
U <Unlock Code>
Set Baud Rate
B <Baud Rate> <stop bit>
Echo
A <setting>
Write to RAM
W <start address> <number of bytes>
Read Memory
R <address> <number of bytes>
Prepare sector(s) for
write operation
P <start sector number> <end sector number>
Copy RAM to Flash
C <Flash address> <RAM address> <number of bytes>
Go
G <address> <Mode>
Erase sector(s)
E <start sector number> <end sector number>
Blank check sector(s)
I <start sector number> <end sector number>