4 years ago.

PWM

HI,

does this board support PWM?

Question relating to:

The LPC11U35 QuickStart Board from Embedded Artists is a easy to use ARM Cortex-M0 rapid prototyping board in a breadboard-friendly 30-pin DIL format. The board targets smaller control applications as …

1 Answer

4 years ago.

Hi Chris,

Looks like that platform does support PWM, but it's not currently shown in the pinout diagram.

According to the source code, the following pins support PWM:

P0_8, P1_13
P0_9, P1_14
P0_10, P1_15
P0_21
P0_22, P1_23
P0_18, P1_24
P0_19, P1_25
P0_1, P1_26
P0_13, P1_0
P0_14, P1_1
P0_15, P1_2

If I listed pins on the same line, there's a chance you might have trouble using both of the pins with differing PWM settings at the same time. This is because they use the same underlying PWM peripheral. I'm honestly not sure and I don't have a board here to test it out. That might not be the case at all, but I just thought I'd mention it in case you observe weird behavior in that situation.

If you want to explore the source code, here's the place where I found this info: https://github.com/mbedmicro/mbed/blob/master/libraries/mbed/targets/hal/TARGET_NXP/TARGET_LPC11UXX/TARGET_LPC11U35_401/PeripheralPins.c#L98

Accepted Answer

The pins listed in that file for CT32B1 are not usable: That timer is already used for the timer/ticker/wait functions (so you can use it, if you don't need those). If you really want those, and not those belonging to CT32B0, you can switch in the us_ticker_api code the timer used for that.

All others are usable, only different pins belonging to the same timer module will have equal period.

posted by Erik - 11 Mar 2016

Thanks for clarifying Erik!

Just to be explicit, that means you can use the following pins:

P0_8, P1_13
P0_9, P1_14
P0_10, P1_15
P0_21
P0_22, P1_23
P0_18, P1_24
P0_19, P1_25
P0_1, P1_26

Where pins that are on the same lines must have the same period if they are both in use.

posted by Brian Daniels 11 Mar 2016