NXP Semiconductors LPC24XX UM10237 - Manual (Page 702)

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User manual Rev. 04 — 26 August 2009 702 of 792
NXP Semiconductors
UM10237
Chapter 31: LPC24XX On-chip bootloader for flashless parts
[1] ISP entry after reset uses the on chip IRC and PLL to run the device at CCLK = 14.748 MHz
6.3 Echo
6.4 Write to RAM
The host should send the data only after receiving the CMD_SUCCESS return code. The
host should send the check-sum after transmitting 20 UU-encoded lines. The checksum is
generated by adding raw data (before UU-encoding) bytes and is reset 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. When the data fits in less then
20 UU-encoded lines then the check-sum should be of the actual number of bytes sent.
The ISP command handler compares it with the check-sum of the received bytes. If the
check-sum matches, the ISP command handler responds with "OK" to
Return Code CMD_SUCCESS |
INVALID_BAUD_RATE |
INVALID_STOP_BIT |
PARAM_ERROR
Description This command is used to change the baud rate. The new baud rate is effective
after the command handler sends the CMD_SUCCESS return code.
Example "B 57600 1" sets the serial port to baud rate 57600 bps and 1 stop bit.
Table 633. Correlation between possible ISP baudrates and CCLK frequency (in MHz)
ISP Baudrate .vs.
CCLK Frequency 9600 19200 38400 57600 115200 230400
10.0000 + + +
11.0592 + + +
12.2880 + + +
14.7456 [1] + + + + + +
15.3600 +
18.4320 + + +
19.6608 + + +
24.5760 + + +
25.0000 + + +
Table 632. ISP Set Baud Rate command
Command B
Table 634. ISP Echo command
Command A
Input Setting: ON = 1 | OFF = 0
Return Code CMD_SUCCESS |
PARAM_ERROR
Description The default setting for echo command is ON. When ON the ISP command handler
sends the received serial data back to the host.
Example "A 0" turns echo off.