Philips LPC2119 User Manual page 230

Philips Semiconductors Preliminary User Manual
ARM-based Microcontroller LPC2119/2129/2292/2294
ISP Command Format
"Command Parameter_0 Parameter_1 ... Parameter_n<CR><LF>" "Data" (Applicable only in case of Write commands)
ISP Response Format
"Return_Code<CR><LF>Response_0<CR><LF>Response_1<CR><LF> ... Response_n<CR><LF>" "Data" (Applicable in case
of Read commands)
ISP Data Format
The data stream is in UU-encode 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.
A description of UU-encode is available at http://www.wotsit.org.
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.
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.
Interrupts during ISP
Boot block Interrupt vectors located in the boot sector of the flash are active after any reset.
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.
RAM used by ISP command handler
ISP commands use on-chip RAM from 0x4000 0120 to 0x4000 01FF. 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. The
maximum stack usage is 256 bytes and it grows downwards.
RAM used by IAP command handler
Flash programming commands use top 32 bytes of on-chip RAM. The maximum stack usage in the user allocated stack space
is 128 bytes and it grows downwards.
Flash Memory System and Programming 230 January 08, 2004