Content originally posted in LPCWare by LabRat on Fri Mar 28 06:06:29 MST 2014
:quest:
In-System Programming (ISP):
UM:
Quote:
5.3 Pin description
The parts support ISP via the USART0, C_CAN, or USB interfaces. The ISP mode is
determined by the state of two pins at boot time:
The ISP pin assignment is different for each package, so that the fewest functions
possible are blocked. No more than four pins must be set aside for entering ISP in any
ISP mode. The boot code assigns two ISP pins for each package which are probed when
the part boots to determine whether or not to enter ISP mode. Once the ISP mode has
been determined, the boot loader configures the necessary serial pins for each package.
UM10736
Chapter 5: LPC15xx Boot process
Rev. 1 — 13 February 2014 User manual
Table 89. ISP modes
ISP mode[color=#0f0] ISP_0 ISP_1[/color] Description
No ISP [color=#0f0]HIGH HIGH[/color] ISP bypassed. [color=#f00]Part attempts to boot from flash.[/color]
If the part is not programmed or contains invalid user
code, this mode will enter ISP via USB.
C_CAN[color=#0f0] HIGH LOW[/color] [color=#f00]Part enters ISP via C_CAN[/color].
USB[color=#0f0] LOW HIGH[/color][color=#f00] Part enters ISP via USB[/color].
USART0[color=#0f0] LOW LOW[/color] [color=#f00]Part enters ISP via USART0[/color].
This two pins are selecting a bootloader (UART/USB/CAN).
So if you connect a LED to one of this pins, it's low and you are starting a bootloader!!
Therefore it's useful to add a jumper to GND and pull these pins up (10k)...
