NXP Semiconductors LPC24XX UM10237 - Manual (Page 679)

UM10237_4 © NXP B.V. 2009. All rights reserved.
User manual Rev. 04 — 26 August 2009 679 of 792
NXP Semiconductors
UM10237
Chapter 30: LPC24XX Flash memory programming firmware
A description of UU-encode is available at the wotsit webpage.
5.2.4 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.
5.2.5 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.
5.2.6 Interrupts during ISP
The boot block interrupt vectors located in the boot block of the Flash are active after any
reset.
5.2.7 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.
5.2.8 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.
5.2.9 RAM used by IAP command handler
Flash programming commands use the top 32 bytes of on-chip RAM. The maximum stack
usage in the user allocated stack space is 128 bytes and it grows downwards.
5.2.10 RAM used by RealMonitor
The RealMonitor uses on-chip RAM from 0x4000 0040 to 0x4000 011F. The user could
use this area if RealMonitor based debug is not required. The Flash boot loader does not
initialize the stack for RealMonitor.