which pins for ISP mode UART0 programming?

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which pins for ISP mode UART0 programming?

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lpcware
NXP Employee
NXP Employee
Content originally posted in LPCWare by vladimirro on Tue Jan 20 12:54:57 MST 2015
Hello

I am currently in a design phase of an application which uses two UARTS, This is why i chose LPC1225.
The problem which I am facing now is which UART pins are actually used for ISP programming?

DT says that I should use UART0 pins (RXD0 and TXD0) to program the flash in the chip. That's cool but UM says that RXD0 and TXD0 are available on two different ports (RXD0 on PIO0_1 and PIO2_1, TXD0 on PIO0_2 and PIO2_2) which can be read in the pin multiplexing chapter.

Can I use either of those pins to program the device? Can I use for example PIO0_1 and PIO0_2 to communicate with another device and PIO2_1, PIO2_2 for ISP programming only?

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lpcware
NXP Employee
NXP Employee
Content originally posted in LPCWare by starblue on Wed Jan 21 08:12:51 MST 2015

Quote: starblue
not in the chapter documenting all the pins and their functions



Seems I guessed wrong w.r.t. LPC12xx.  In the latest User Manual dated 2014-05-27 it is indeed documented in the chapter on pin functions.
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lpcware
NXP Employee
NXP Employee
Content originally posted in LPCWare by vladimirro on Wed Jan 21 07:35:07 MST 2015
Thank you very much guys for fast reply. That saved a lot of my time and solved my problem.

BTW are you sure that the infromation you gave me is in the UM? I still can't find it.
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lpcware
NXP Employee
NXP Employee
Content originally posted in LPCWare by starblue on Wed Jan 21 01:51:38 MST 2015
Usually (I don't know whether it's the case for LPC12xx) this is documented in the user manual in the chapter on the boot loader, but not in the chapter documenting all the pins and their functions. The same goes for the pins which determine whether ISP is entered and which boot method is used.
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lpcware
NXP Employee
NXP Employee
Content originally posted in LPCWare by nerd herd on Tue Jan 20 15:07:00 MST 2015
Hi vladimirro,

I can understand your confusion. The reason why two different sets of pins can function as UART0 is to give the user flexibility with multiplexed pins. The way we go about this is based on the value of certain bits in the IOCON register. That said, ISP programming happens after a reset, meaning the pins have a default state in what their function are upon reset. In this case, PIO0_1 and PIO_02 are the only UART0 pins you can use for ISP programming. If you look at the user's manual one more time, you will notice that those are the only UART0 pins that explicitly say they can be used for ISP programming.
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