NXP Semiconductors LPC24XX UM10237 - Manual (Page 703)

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User manual Rev. 04 — 26 August 2009 703 of 792
NXP Semiconductors
UM10237
Chapter 31: LPC24XX On-chip bootloader for flashless parts
continue further transmission. If the check-sum does not match, the ISP command
handler responds with "RESEND". In response the host should retransmit the
bytes.
6.5 Read Memory
The data stream is followed by the command success return code. The check-sum is sent
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 is
of actual number of bytes sent. The host should compare it with the checksum of the
received bytes. If the check-sum matches then the host should respond with
"OK" to continue further transmission. If the check-sum does not match then
the host should respond with "RESEND". In response the ISP command
handler sends the data again.
Table 635. ISP Write to RAM command
Command W
Input Start Address: RAM address where data bytes are to be written. This address
should be a word boundary.
Number of Bytes: Number of bytes to be written. Count should be a multiple of 4
Return Code CMD_SUCCESS |
ADDR_ERROR (Address not on word boundary) |
ADDR_NOT_MAPPED |
COUNT_ERROR (Byte count is not multiple of 4) |
PARAM_ERROR |
CODE_READ_PROTECTION_ENABLED
Description This command is used to download data to RAM. Data should be in UU-encoded
format. This command is blocked when code read protection is enabled.
Example "W 1073742336 4" writes 4 bytes of data to address 0x4000 0200.
Table 636. ISP Read Memory command
Command R
Input Start Address: Address from where data bytes are to be read. This address
should be a word boundary.
Number of Bytes: Number of bytes to be read. Count should be a multiple of 4.
Return Code CMD_SUCCESS followed by |
ADDR_ERROR (Address not on word boundary) |
ADDR_NOT_MAPPED |
COUNT_ERROR (Byte count is not a multiple of 4) |
PARAM_ERROR |
CODE_READ_PROTECTION_ENABLED
Description This command is used to read data from RAM.
Example "R 1073741824 4" reads 4 bytes of data from address 0x4000 0000.