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Hi
I am using the PSOC kit with the CY8C3866 (ES2 silicon)
I have to use the DAC, but the output signal is strange (see attachment). When I set the DAC to a new value, it does not settle like it should in less than 5us
The DAC output is directly into a 1M scope input, DC coupled.
The code, somewhat snipped: (also attached)
// Enable DACs
VDAC8_1_Start();
while (1) {
VDAC8_1_SetValue(100);
for (i=1;i<100;i++) {
value1 = 100;
}
VDAC8_1_SetValue(0);
for (i=1;i<100;i++) {
value1 = 100;
}
}
Solved! Go to Solution.
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PSoC 3
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Keep in mind the VDAC output is NOT a voltage source. For the 1V range
its output Z is 4K , 4V range 16K, typical values. So if you have any signif-
icant C on pin that will show up as RC charging waveshape.
Your waveshape looks like C ramping from a current source. Or RC over a short
span.
I noticed you are using an ES version of PSOC 3, and old Creator. There have
been many bug fixes and components fixes/upgrades since then. Creator is now
3.2 SP1. You should, if you can, upgrade.
Regards, Dana.
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Keep in mind the VDAC output is NOT a voltage source. For the 1V range
its output Z is 4K , 4V range 16K, typical values. So if you have any signif-
icant C on pin that will show up as RC charging waveshape.
Your waveshape looks like C ramping from a current source. Or RC over a short
span.
I noticed you are using an ES version of PSOC 3, and old Creator. There have
been many bug fixes and components fixes/upgrades since then. Creator is now
3.2 SP1. You should, if you can, upgrade.
Regards, Dana.
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If you want a true V source out of the VDAC pass it thru OpAmp configed as
buffer, high power setting.
Regards, Dana.
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Thank you for the comments. It is really embarrasing, it was the probe compensation 😉
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Thank you for the comments. It is really embarrasing, it was the probe compensation 😉