Analog to Digital Converter Type 1 FAQ for C2000

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Introduction

This topic is a list of frequently asked questions that users have when using the Analog to Digital Converter of type 1. ADC type 1 is the 2nd generation ADC module released for the C28x devices. ADC type 1 is found on the 280x family which includes 2801, 2802, 2806, 2808, 2809, 28015, 28016, 28044.

Electrical Specifications

Electrical specifications can change between devices, peripheral types and device families. Always refer to the data manual and errata for a particular device for Electrical Specifications.


ADC Type Summary

The following table summarizes the different type of ADC modules found on C28x devices.

C2000 ADC Module Types
Type
Description
Devices
Documentation
0
Original C28x ADC module
281x
TMS320x281x Analog-to-Digital Converter (ADC) Reference Guide (spru060)
1
Added Offset Trim and Reference Select registers
2801, 2802, 2806, 2808, 2809, 28015, 28016, 28044
TMS320x280x 2801x, 2804x Analog-to-Digital Converter(ADC) Module Reference Guide (spru716)
2
Added Internal/External Trim registers
Trim by Device_cal() function call
2833x, 2834x
TMS320x2833x, 2823x Analog-to-Digital Converter (ADC) Module Reference Guide (spru812)
3
Different control register interface, converts from 0 to 3.3 V fixed scale range, supports ratiometric VREFHI/VREFLO references
2802x, 2803x

2806x
TMS320x2802x, 2803 Piccolo Analog-to-Digital Converter and Comparator Ref. Guide (spruge5)

TMS320x2806x Piccolo Technical Reference Guide (SPRUH18)


Frequently asked questions for ADC Type 1

Q: I measured ADCREFP and ADCREFM. In the datasheet only a typical value is specified not a min/max. How can I tell if my device is in spec?

These signals are internally generated voltages for use by the internal ADC only. These are fully tested at by TI at production time and will not be out of spec for the device. The only reason these signals are brought outside the device is for external bulk cap. The Data Manual values are only there to give a ballpark of where the voltages will be and this is why there is no max/min.

Q: What’s the difference of SEQ1INT, SEQ2INT and ADCINT? When would SEQ1INT can be triggerd?

SEQ1INT and SEQ2INT are the end-of-sequence interrupts for ADC sequencers #1 and #2 respectively. ADCINT is legacy for backwards compatibility with 281x device, and is triggered by both SEQ1 or SEQ2 on end-of-sequence. In the ADCINT ISR, software would check the sequencer flags to determine which sequencer triggered the interrupt. SEQ1INT and SEQ2INT eliminate the need to do this.

Q: Can I calibrate this ADC?

Yes - please refer to the application note:

Q: The 2833x/2823x devices have an on-chip ADC_cal() function. Is this available on 280x?

No, but calibration can still be achieved - please refer to the application note:

Q: Looking at the calibration app note it appears that you need to physically connect an ADC channel to ground. Is there a way to configure an internal connection to GND for calibration purposes?

There is no way to connect the GND to a pin internally for calibration.