emailcausey reacted to TI_Trey in Measuring external voltage
The error you're seeing could also be caused by the first sample errata on these parts. Basically when you fire off a SOC, the first conversion it does has some error to it. In the examples you should see that two SOC are configured for the same trigger source. The result from the first sample is throw away and the second is used. Make sure you are doing this in your code.
Another thing to consider is that for really high quality A to D conversion you want to buffer the signal you're trying to read. This is more of an issue for dynamic signals, but do be mindful of the impedance you are driving the ADC with.
emailcausey reacted to timotet in Measuring external voltage
I found the document:
TMS320x2802x, 2803x Piccolo Analog-to-Digital
Converter (ADC) and Comparator Reference guide
To be helpful, if you dont have it.
Search for SPRUGE5F on TI's site.
I think in your ADC_init code you want:
ADC_setVoltRefSrc(myAdc, ADC_VoltageRefSrc_Int); // sets adc to internal reference
According to the chips data sheet pin 12 on the Tms320F28027 is VREFLO.
Datasheet also says it always tied to ground.
or for external source:
ADC_setVoltRefSrc(myAdc, ADC_VoltageRefSrc_Ext); // for external reference source
In this case you would have your VREFHI connected to pin 10 on the micro(J5.6 on C2000 launchpad)
I looked at the example you are using and its in there as an internal source.
Hope this helps
emailcausey reacted to TI_Trey in SPI_write8
It looks like you're on the right track.
Given that you're using Tim's code, I would suspect a wiring error. Can you double check all of your wires? Reset and the Chip enable/select are two very important lines that could cause this to fail. But it could also be any of the serial data lines.
Does the backlight of the LCD come on when you run it? From what I see in the code, if its wired correctly it should turn on even if the communications aren't fully working.