Can someone tell me why this code doesnt do its job? I am new to uVision. The code should turn on the LED diodes as you turn the potentiometer. For example, if its on position 0V the first LED should be lit, and if its on position 3.3V the last one. Tnx in advance
#include <stdio.h> #include <stdlib.h> #include <LPC214x.h>
void delay(int i){ unsigned int j; for(j=0; j < i; j++); }
int main (void) { unsigned int rez; IODIR1 = 0x00FF0000; //diode postavljene kao output AD0CR = 0x00200402; //ADC1: 10-bit AIN1 @ 3MHz
while(1){ AD0CR |= 0x01000000; // start AD konverzije
while ((AD0DR1 & 0x80000000) == 0); // cekanje da se konverzija zavrsi
AD0CR &= ~0x01000000; //stop AD konverzije rez = AD0DR1 & 0x0000FFC0; if(rez < 128) IOSET1 = 1 << 16; else if(rez > 128 && rez < 256) IOSET1 = 1 << 17; else if(rez > 256 && rez < 256+128) IOSET1 = 1 << 18; else if(rez > 256+128 && rez < 512) IOSET1 = 1 << 18; else if(rez > 512 && rez < 512+128) IOSET1 = 1 << 19; else if(rez > 512+128 && rez < 768) IOSET1 = 1 << 20; else if(rez > 768 && rez < 768+128) IOSET1 = 1 << 21; else if(rez > 896 && rez < 1024) IOSET1 = 1 << 22; else IOSET1 = 1 << 23;
delay(100000); }
}
Well, I am not very good at debuging (but I did my best). I put a breakpoint before the if cases, and when I look at the values of rez and val it sais they are 0x00000000 both. This makes sense, because when I run the program only the first LED is on (which is from case rez < 128). Another interesting fact is that the AD0DR1 register is also 0x00000000 (which gives the value to rez and val). Why is it so, I wouldnt know... :/
Are my conversion steps right? 1. I start the conversion 2. Wait for it to finish 3. Stop it
And then I just read the results... It should work... :/
Any ideas?
I don't work with your specific processor, but have you verified that the ADC is powered before you start to initialize it? And have you verified the initialization? What differs compared to sample code available from Keil or NXP?
This line of code
AD0CR = 0x00200402; //ADC1: 10-bit AIN1 @ 3MHz
initializes the ADC (power up and everything needed). There is no sample code that does what I need. Its a slight variation (and I started from it, by modifying it).
I'm pretty sure you have a bit in PCONP that is important too. Just that I do believe it already defaults to the correct value.
But another thing - have you switched the input pin from digital function to analog function? I don't see you assign anything to any PINSELx register.
"But another thing - have you switched the input pin from digital function to analog function? I don't see you assign anything to any PINSELx register."
I dont understand this. The AD0CR controls which channel are you using (the value 0x02 setts this to AIN1). And AIN1 is connected to the potentiometer trough a jumper, so you dont have to initialize the input. Its already connected as default. If you want to take a look here is the schematic http://www.keil.com/mcb2140/mcb2140-schematics.pdf (go to second page)
Did you spend time with the manual, reading about the PINSELx registers?
Dod you read through the full chapter about the ADC in the user manual?
Did you specifically read the information in the paragraph 19.5.3 Accuracy vs. digital receiver?
The NXP user manual is the #1 document to read through when using the processor.
As I said earlier, I don't work with any LPC21xx chips. So I don't have a reason to invest the time to read up on all the details. I spend my time reading the documentation for the processors I use.
But you have a big reason to invest the time with the LPC214x user manual. www.nxp.com/.../UM10139.pdf
It worked, even tough I dont quite get it. I add this code
PINSEL1 = 0x01080000; // Select DAC (AOUT) & AIN1
to the source. Btw, I did read the manual many times... Tnx for your help, both!