LPC550x How do I use all 9 ADCs?

[ianbenton]

I wish to use the LPC550x to replace a LPC1517. It is advertised as having 9 A/D converters, and I need all 9.

However, two A/D pins are occupied by SWCLK and SWDIO.

How do I use all 9 A/Ds?

[ianbenton]

If I switch the pin to analogue input, how do I switch it back to SWDIO for further debugging? 

[xiangjun_rong]

Hi,

I suppose that you can use boot mode to do the switch. You can connect the PIO0_5 pin to a hardware button, when the button is not pressed, the PIO0_5 pin is high, the LPC550x will execute application code in flash, the SWD pin are configure as ADC analog pins by application code.

when the PIO0_5 button is pressed, the PIO0_5 pin is low, the LPC550x will enter boot mode, in the case, the SWD pin are still SWD pin, you can load/debug code via SWD.

Hope it can help you

BR

XiangJun Rong

[xiangjun_rong]

Hi, Benton,

For 64 pin package chip of LPC550x family, there are 9 ADC channels, for the 48 pin package chip of LPC550x family, there are 7 ADC channels.

Regarding the two ADC analog channels pin which are multiplexed with SWD pins:

PIO0_12/ADC0_10/.../SWDIO, and PIO0_11/ADC0_9/..../SWCLK, when you design your development board, I suggest you use a jumper, in detail, you can connect the two pins to the SWD connector directly and connect the two pins to ADC analog signal via jumper. In development stage, you can open the jumper, download/debug without considering the two analog channels. After your project has finished, close the jumper while disconnect the SWD device. You can use a resistor to replace the jumper.

Hope it can help you

BR

XiangJun Rong