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I input a 6bits_code_min=0dec or 6b_code_max=62dec value into the DAC6 by means WriteStall API and I get unexpected Voutput value.
Theoretically the DAC6 datasheets told us:
Vout=(Vrefhi-AGND)*ACap/FCap+AGND
Taking into account my reference Vdd/2+/-BandGap I must to have:
Vout(max)=3.76V
Vout(min)=2.5V
Instead of this I obtain a more or less a Vout=3.7 V and after that the value is going down until reach
aproximattely 2.5V. I put the analog outputs in High Z.
The C code is simple:
#include
"PSoCAPI.h" // PSoC API definitions for all User Modules
#define
DAC_MAX ( 62 ) // Define max DAC value as 62
unsigned
char bDACValue = DAC_MAX; // Variable for the DAC valueunsigned
char j; // Variable for an indexint
i;
void
{
DAC6_Start(DAC6_HIGHPOWER);
main() // Start DAC6 in HIGH power modeBUFFER_Start(BUFFER_HIGHPOWER);
while ( 1 ) // Repeat forever
{
//for(j=0; j<62; j++){
DAC6_WriteStall(bDACValue);
for(i = 0xFF; i != 0; i--); // Delay loop
for (i = 0xFF ; i != 0 ; i--); // Delay loopfor (i = 0xFF ; i != 0 ; i--); // Delay loop
}/*while*/ /*main*/
Anyone could tell me what's going on? Thanks
}
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PSoC 1
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Some points to check:
1. What is the column clock setting for the DAC? Depending on the power you operate, there is a maximum column clock limitation. If the column clock is more than the limit, then the DAC output will not be as expected.
2. Is the DAC set to signed or unsigned? If set to unsigned, you will get REFLO at the output, ie, 1.3V. For a value of 62, you should get REFHI which is 3.8V
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I'm using a 136KHz frecuency column clock. Much lower than the 3.2MHz let it with high Power
use modele way.
The DAC is signed?
The input data is OffsetBinary. I shoudl to obtain following the formula a values between 2,6V and 3,9V.
I got a ramp, but is not between the values I hope.