topic Re: How can changing P1_2 state from low to high output be seen in P1_6? in LPC Microcontrollers

How can changing P1_2 state from low to high output be seen in P1_6?

Gaico — Wed, 14 Sep 2022 18:54:33 GMT

Hello,

We are currently trying to figure out why two pins seem almost interchangeable in controlling a HIGH/LOW output on the OM13084 board. Header: J1.19.

The setup is as follows:

An oscilloscope is connected to pin P1_6 on the board. When changing the state of the P1_6 pin (which is set to GPIO output) from low to high, nothing happens. When then changing the state of the P1_2 pin, we can see a change in output as expected when trying to change the P1_6 pin.

Short notation of the question is thus: Is there a reason as to why I cannot directly change the state of the P1_6 pin, only through changing P1_2? I am not configuring them any different in code.

I hope this question is not too vague, but I would appreciate any kind of input!

Take care

Re: How can changing P1_2 state from low to high output be seen in P1_6?

Alice_Yang — Thu, 15 Sep 2022 01:55:49 GMT

Hello,

Please take a picture about your hardware connection when measure P1_6,

also show your code.

Alice

Re: How can changing P1_2 state from low to high output be seen in P1_6?

frank_m — Thu, 15 Sep 2022 04:51:14 GMT

> An oscilloscope is connected to pin P1_6 on the board. When changing the state of the P1_6 pin (which is set to GPIO output) from low to high, nothing happens. When then changing the state of the P1_2 pin, we can see a change in output as expected when trying to change the P1_6 pin.

First thing I would do ist to measure the connections from J1.19 to both pins with an Ohmmeter, with power off.

I guess you have checked the schematics already.

Re: How can changing P1_2 state from low to high output be seen in P1_6?

Gaico — Thu, 15 Sep 2022 07:59:42 GMT

Hi Alice,

Thank you for your reply. As I don't reckon the issue is caused by faulty hardware (as I only read out the pin, same as say putting an LED on pin P1_9), I will for now only cover the software I have.

Initializer code is as follows (within main):

Chip_GPIO_SetPinDIROutput(LPC_GPIO_PORT, 1, 2); //for some reason this one triggers on the 1,9 port Chip_GPIO_SetPinDIROutput(LPC_GPIO_PORT, 1, 9); //port output wire is connected to Chip_SCU_PinMuxSet(9,0, SCU_PINIO_FAST); // SCU_MODE_FUNC0 | SCU_PINIO_FAST); Chip_SCU_PinMuxSet(9,1, SCU_PINIO_FAST); // SCU_MODE_FUNC0 | SCU_PINIO_FAST); Chip_GPIO_SetPinDIROutput(LPC_GPIO_PORT,4,12); Chip_GPIO_SetPinDIROutput(LPC_GPIO_PORT,4,13);

Then the functioning code is as follows (within an infinite loop):

Board_LED_Set(1, true); //Chip_GPIO_SetPinState(LPC_GPIO_PORT, 1, 2, true); //outputs on 1,9? Chip_GPIO_SetPinState(LPC_GPIO_PORT, 1, 9, true); //nothing on 1,9? _delay_ms(200); //wait, custom function //Chip_GPIO_SetPinState(LPC_GPIO_PORT, 1, 2, false); // deactivate power Chip_GPIO_SetPinState(LPC_GPIO_PORT, 1, 9, false); // deactivate power Board_LED_Set(1, false);

With maybe the important functions for how the pinstate is set:

/** * @brief Set GPIO direction for a single GPIO pin to an output * pGPIO : The base of GPIO peripheral on the chip * port : GPIO Port number where @a pin is located * pin : GPIO pin to set direction on as output * @return Nothing */ STATIC INLINE void Chip_GPIO_SetPinDIROutput(LPC_GPIO_T *pGPIO, uint8_t port, uint8_t pin) { pGPIO->DIR[port] |= 1UL << pin; }

/** * @brief Set a GPIO pin state via the GPIO byte register * pGPIO : The base of GPIO peripheral on the chip * port : GPIO Port number where @a pin is located * pin : GPIO pin to set * setting : true for high, false for low * @return Nothing * @note This function replaces Chip_GPIO_WritePortBit() */ STATIC INLINE void Chip_GPIO_SetPinState(LPC_GPIO_T *pGPIO, uint8_t port, uint8_t pin, bool setting) { pGPIO->B[port][pin] = setting; }

I am not seeing anything being done differently, but I might be overlooking something.

Re: How can changing P1_2 state from low to high output be seen in P1_6?

Gaico — Thu, 15 Sep 2022 09:00:50 GMT

I found the issue, it was my mistake for looking in the wrong place.

I was assuming the name(s) on the demo board were the same as the names needed in the code.

If looking in the datasheet, pin P1_6 has GPIO1[2], which was used in the code.

After doing this with another test port (P1_7 which turned into GPIO1[0]) everything works as expected.