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UM10375
All information provided in this document is subject to legal disclaimers.
© NXP B.V. 2011. All rights reserved.
User manual
Rev. 3 — 14 June 2011
322 of 368
NXP Semiconductors
UM10375
Chapter 21: LPC13xx Flash memory programming firmware
21.8.3 ISP data format
The data stream is in UU-encoded format. The UU-encode algorithm converts 3 bytes of
binary data in to 4 bytes of printable ASCII character set. It is more efficient than Hex
format which converts 1 byte of binary data in to 2 bytes of ASCII hex. The sender should
send 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.
21.8.4 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 (stop) is sent to
stop the flow of data. Data flow is resumed by sending the ASCII control character DC1
(start). The host should also support the same flow control scheme.
21.8.5 ISP command abort
Commands can be aborted by sending the ASCII control character "ESC". 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.
21.8.6 Interrupts during ISP
The boot block interrupt vectors located in the boot block of the flash are active after any
reset.
21.8.7 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.
21.8.8 RAM used by ISP command handler
ISP commands use on-chip RAM from 0x1000 017C to 0x1000 025B. The user could use
this area, but the contents may be lost upon reset. Flash programming commands use the
top 32 bytes of on-chip RAM. The stack is located at RAM top
32 bytes. The maximum
stack usage is 256 bytes and grows downwards.
21.8.9 RAM used by IAP command handler
Flash programming commands use the top 32 bytes of on-chip RAM. The maximum stack
usage in the user allocated stack space is 128 bytes and grows downwards.