Datasheet

UM10398 All information provided in this document is subject to legal disclaimers. © NXP B.V. 2014. All rights reserved.
User manual Rev. 12.3 — 10 June 2014 417 of 547
NXP Semiconductors
UM10398
Chapter 26: LPC111x/LPC11Cxx Flash programming firmware
Remark: The sampling of pin PIO0_1 can be disabled through programming flash
location 0x0000 02FC (see Section 26.3.8.1
).
26.3.2 Memory map after any reset
The boot block is 16 kB in size. The boot block is located in the memory region starting
from the address 0x1FFF 0000. The bootloader is designed to run from this memory area,
but both the ISP and IAP software use parts of the on-chip RAM. The RAM usage is
described later in this chapter. The interrupt vectors residing in the boot block of the
on-chip flash memory also become active after reset, i.e., the bottom 512 bytes of the
boot block are also visible in the memory region starting from the address 0x0000 0000.
26.3.3 Criterion for Valid User Code
Criterion for valid user code: The reserved Cortex-M0 exception vector location 7 (offset
0x 0000 001C in the vector table) should contain the 2’s complement of the check-sum of
table entries 0 through 6. This causes the checksum of the first 8 table entries to be 0. The
bootloader code checksums the first 8 locations in sector 0 of the flash. If the result is 0,
then execution control is transferred to the user code.
If the signature is not valid, the auto-baud routine synchronizes with the host via serial port
0. The host should send a ’?’ (0x3F) as a synchronization character and wait for a
response. The host side serial port settings should be 8 data bits, 1 stop bit and no parity.
The auto-baud routine measures the bit time of the received synchronization character in
terms of its own frequency and programs the baud rate generator of the serial port. It also
sends an ASCII string ("Synchronized<CR><LF>") to the host. In response to this host
should send the same string ("Synchronized<CR><LF>"). The auto-baud routine looks at
the received characters to verify synchronization. If synchronization is verified then
"OK<CR><LF>" string is sent to the host. The host should respond by sending the crystal
frequency (in kHz) at which the part is running. For example, if the part is running at 10
MHz, the response from the host should be "10000<CR><LF>". "OK<CR><LF>" string is
sent to the host after receiving the crystal frequency. If synchronization is not verified then
the auto-baud routine waits again for a synchronization character. For auto-baud to work
correctly in case of user invoked ISP, the CCLK frequency should be greater than or equal
to 10 MHz.
Once the crystal frequency is received the part is initialized and the ISP command handler
is invoked. For safety reasons an "Unlock" command is required before executing the
commands resulting in flash erase/write operations and the "Go" command. The rest of
the commands can be executed without the unlock command. The Unlock command is
required to be executed once per ISP session. The Unlock command is explained in
Section 26.5 “
UART ISP commands” on page 424.