UM10503
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© NXP B.V. 2012. All rights reserved.
User manual
Rev. 1.3 — 6 July 2012
1173 of 1269
NXP Semiconductors
UM10503
Chapter 46: LPC43xx flash programming/ISP and IAP
the check-sum after transmitting 20 UU-encoded lines. The length of any UU-encoded line
should not exceed 61 characters (bytes) i.e. it can hold 45 data bytes. The receiver should
compare it with the check-sum of the received bytes. If the check-sum matches then the
receiver should respond with "OK<CR><LF>" to continue further transmission. If the
check-sum does not match the receiver should respond with "RESEND<CR><LF>". In
response the sender should retransmit the bytes.
46.4.5.4 ISP flow control
A software XON/XOFF flow control scheme is used to prevent data loss due to buffer
overrun. When the data arrives rapidly, the ASCII control character DC3 (0x13) is sent to
stop the flow of data. Data flow is resumed by sending the ASCII control character DC1
(0x11). The host should also support the same flow control scheme.
46.4.5.5 ISP command abort
Commands can be aborted by sending the ASCII control character "ESC" (0x1B). This
feature is not documented as a command under "ISP Commands" section. Once the
escape code is received the ISP command handler waits for a new command.
46.4.5.6 Interrupts during IAP
The on-chip flash memory is not accessible during erase/write operations. When the user
application code starts executing the interrupt vectors from the user flash area are active.
The user should either disable interrupts, or ensure that user interrupt vectors are active in
RAM and that the interrupt handlers reside in RAM, before making a flash erase/write IAP
call. The IAP code does not use or disable interrupts.
46.4.5.7 RAM used by ISP command handler
ISP commands use on-chip RAM from 0x1008 0000 to 0x1008 0200. The user could use
this area, but the contents may be lost upon reset. Flash programming commands use the
top 32 B of on-chip RAM. The stack is located at RAM top - 32. The maximum stack
usage is 256 B and grows downwards.
46.4.5.8 RAM used by IAP command handler
Flash programming commands use the top 32 B of on-chip RAM. The maximum stack
usage in the user allocated stack space is 256 B and grows downwards. The stack space
is excluding usage of IAP Set active partition command. The Set active partition command
requires an additional 2200 B in stack additionally for a maximum of 2456 B.
46.4.6 Flash signature generation
For parts with on-chip flash, a hardware flash signature generation capability is built into
the flash memory. This feature can be used to create a signature that can then be used to
verify flash contents. Details of flash signature generation are shown in
.