Content originally posted in LPCWare by verybadalloc on Wed Feb 24 22:59:14 MST 2016
Hello,
I have been getting some really weird voltages on the xplorer ngx 4330 board, and I was hoping I would get some kind of explanation of what I doing wrong. I am using LPCXpresso 8.
I ran the blinky project from the examples provided with the Xpresso, and I am able to see that it runs (the LED is blinking). I then get the oscilloscope, and start probing each pin on the board. The obvious ones, like 5V and 3.3V report correct values. However, a large number of pins seem to be giving me values, even though I am not using them. For example:
- I get 0.7V on the pins GPIO5[7], GPIO0[9] and GPIO1[10]
- I get 3.3V on the pins GPIO0[8], GPIO1[9], GPIO0[7] and GPIO1[11]
- I get 3.1V on GPIO0[4], GPIO3[5], GPIO3[7], and GPIO31[1].
What is really frustrating is that these values don't seem to go away, even when I try to use these GPIO to write values from the MCU. For example, using the following code:
Chip_SCU_PinMuxSet(5, 7, SCU_PINIO_FAST); //5_7
Chip_GPIO_SetPinDIROutput(LPC_GPIO_PORT, 5, 7);
Chip_GPIO_SetPinOutHigh(LPC_GPIO_PORT, 5, 7);
I am still seeing the 0.7 V output at the pin.
The only pins that I can actually program to are GPIO0[2], GPIO1[12], GPIO5[0], GPIO0[3], GPIO0[1] and GPIO0[0].
Also, I had a second question with regards to generating a clock signal. Currently, the SCK pin outputs a clock signal at 204MHz, the frequency of the MCU. Is it possible to output a clock signal at 20MHz, on a different pin? I am thinking just a pin that changes state every 10 cycles.
Thanks again for your help!
