topic Re: 16 bit microcontroller ATD questions in S12 / MagniV Microcontrollers

16 bit microcontroller ATD questions

EagleBeak — Wed, 20 Sep 2006 05:29:54 GMT

I would like to ask someone about some particulars of the ATD system on MC9S12E128.

I am reading the registers as right justified, 10 bit, unsigned and not getting what I expect.

The VCC of the micro is 3V but the VRH and VRL range is 4.0V.

I placed 3 volts at the input of a channel (under emulator control ) but am reading 2.5V.

By my calculation I'm about a half a volt off on my readings, though they are fairly consistent.

If I ground the input, it reads close to zero most of the time, within 3%.

Any suggestions?

Thanks,

Eagle Beak

Re: 16 bit microcontroller ATD questions

DanielM — Wed, 20 Sep 2006 14:44:31 GMT

VRH cannot be above VDDA - read the spec! The allowed range for VRH is from VDDA/2 to VDDA.

BTW, 3V is uder spec limit for VDDA, VDDX and VDDR as well. The minimum supply voltage is 3.135V.

Daniel

Message Edited by DanielM on 2006-09-20 02:47 AM

Re: 16 bit microcontroller ATD questions

EagleBeak — Wed, 20 Sep 2006 22:47:25 GMT

Daniel,

I suspected what you said is true but I couldn't find the spec you refer to. Is it in the data sheet?

Thanks so much,

Eagle Beak

Re: 16 bit microcontroller ATD questions

EagleBeak — Thu, 21 Sep 2006 00:30:02 GMT

Daniel,

Woops, I found the spec. Thanks for the quick response to my question. It was a life saver.

Eagle Beak, aka Scott

Re: 16 bit microcontroller ATD questions

Vsousa — Tue, 22 Jan 2008 02:53:18 GMT

Hi,

I'm having some troubles with ATD module of the MC9S12E128. I'm using the high chanel and the CH7 as digital IOs and the other pins as analogic inputs. I don't know why, the AN4, AN5 and AN6 operation, doesn't sets the ATDSTAT1 with their corresponding CCFx Flags.
I'm sending a piece of code to show the ATD initialization and using..

----------------------------------------------------------------------
void AdcConfig(void){
     ATDDIEN0 = 0xFF;   // Enable digital ports to PTADHi.
     ATDDIEN1 = 0x80;   // Enable digital ports to PTADLo bit7 and analog to others.
     ATDCTL2 = 0xC0;   // Normal ATD functionality and enable Fast Clear Flag
     ATDCTL4 = 0x21;   // ATD Clock prescaler = Divide by 4 due the max/min clock freq
     ATDTEST1 = 0x00;   // No Special conversion chanel
}

int Adc6(void){
ATDCTL5 = 0x86;               // Right justified data in the result registers - turn on ch6
while (!(ATDSTAT1 & CCF6));   //Wait
return ATDDR6;
}

int Adc5(void){
ATDCTL5 = 0x85;               // Right justified data in the result registers - turn on ch5
while (!(ATDSTAT1 & CCF5));   //Wait
return ATDDR5;
}

int Adc4(void){
ATDCTL5 = 0x84;               // Right justified data in the result registers - turn on ch4
while (!(ATDSTAT1 & CCF4));
return ATDDR4;
}

int Adc3(void){
ATDCTL5 = 0x83;               // Right justified data in the result registers - turn on ch3
while (!(ATDSTAT1 & CCF3));   //Wait
return ATDDR3;
}

..... until CH0

The chanels below CH4, works fine and the digital pins too. I don't know what's happening,

Please, If you could help me..

Thank you.