Datasheet

User manual Rev. 12.3 — 10 June 2014 423 of 547

NXP Semiconductors

UM10398

Chapter 26: LPC111x/LPC11Cxx Flash programming firmware

26.4 UART Communication protocol

All UART ISP commands should be sent as single ASCII strings. Strings should be

terminated with Carriage Return (CR) and/or Line Feed (LF) control characters. Extra

<CR> and <LF> characters are ignored. All ISP responses are sent as <CR><LF>

terminated ASCII strings. Data is sent and received in UU-encoded format.

26.4.1 UART ISP command format

"Command Parameter_0 Parameter_1 ... Parameter_n<CR><LF>" "Data" (Data only for

Write commands).

26.4.2 UART ISP response format

"Return_Code<CR><LF>Response_0<CR><LF>Response_1<CR><LF> ...

Response_n<CR><LF>" "Data" (Data only for Read commands).

26.4.3 UART 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.

26.4.4 UART 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.

26.4.5 UART 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.

26.4.6 Interrupts during UART ISP

The boot block interrupt vectors located in the boot block of the flash are active after any

reset.