UM11029
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© NXP B.V. 2017. All rights reserved.
User manual
Rev. 1.0 — 16 June 2017
49 of 515
NXP Semiconductors
UM11029
Chapter 5: LPC84x ISP and IAP
5.8.2 SH_CMD_RESET (0xA2) command
This command can be used to reset the LPC84x. This command has no response.
5.8.3 SH_CMD_BOOT (0xA3) command
This command can be used to boot the application currently programmed into flash, boot
address starting at 0x0. This command has a response only if the boot image does not
have a valid checksum.
5.8.4 SH_CMD_CHECK_IMAGE (0xA4) command
This command can be used to check the checksum value of the application currently
programmed into FLASH. The command verifies the checksum of the image. If the
checksum is valid, a response value of 0 is returned, otherwise, the checksum value is
returned.
5.8.5 SH_CMD_PROBE (0xA5) command
The probe command is used to select either the I2C or SPI interface when in
auto-detection mode. This command is required when booting into the I2C/SPI ISP mode
from a reset condition. The probe command data is accepted on the supported I2C or SPI
Table 55.
Command packet
Field
Offset Size (bytes) Value
Description
command
0x0
0x1
0xA2
'Reset' command identifier
Table 56.
Command packet
Field
Offset Size (bytes) Value
Description
command
0x0
0x1
0xA3
'Boot' command identifier
Table 57.
Response packet
Field
Offset Size (bytes) Value
Description
sop
0x0
0x1
0x55
Start of packet identifier
command
0x1
0x1
0xA3
Processed command identifier
length
0x2
0x2
0x4
Length of the response packet on an error
errorCode
0x4
0x4
Error code
Boot prevention due to invalid checksum.
Table 58.
Command packet
Field
Offset Size (bytes) Value
Description
command
0x0
0x1
0xA4
'Check image' command identifier
Table 59.
Response packet
Field
Offset Size (bytes) Value
Description
sop
0x0
0x1
0x55
Start of packet identifier
command
0x1
0x1
0xA4
Processed command identifier
length
0x2
0x2
0x04
Length of the response packet
checksum
0x4
0x4
CRC32 value
0x0 if match, otherwise the checksum value.