TI PGA970EVM awesome idea for an SOC, but can Texas Instruments get it work outside their lab?

Thread Starter

Jaime Fischer

Joined Dec 15, 2018
3
Being very impressed with the specs of the SOC PGA970, an awesome SOC designed to excite, condition then digitize analog LVDT sensors!
Being so enamored with the idea of such a tiny device to utilize LVDT sensors, I invested in a PGA970EVM package from Texas Instruments.
I spent many hours with the device trying to make it operate with no joy.
3 replacements were sent with the comment that new SOCs were soldered to the boards.
Each EVM would produce a sine wave of excellent quality the first time it was powered on.
After the first write cycle to change the parameters of the sine wave (frequency and amplitude), the SOC would not produce a sine wave.
I have carefully verified grounding of my equipment for protection against ESD, power supply voltage quality (very clean DC), AND have provided captures of wave forms during SPI communication during read/write cycles. (also very clean wave forms)
After several replacements and direct support with a Texas Instrument engineer, he believes it is some mistake on my part but can not say what it is.
After reading all of the E2E posts regarding this EVM unit, it is obvious that I am not the only one to suffer this issue.
Using a USB2ANY that was tested functional in the TI lab, mass read/writes to the device produce random data written to the registers.
When performing read/writes to individual registers the expected data is written to the registers.
I have requested an RMA for refund the 3rd EVM module.
at the e2e.ti.com a search for PGA970EVM will show produce the post many have made.
This is a big blow to my confidence..... Is it actually possible that TI has provided an evaluation module with defective firmware for the PGA970?

This is the sine wave output after mass write
sine_wave.jpg
This is the SPI communication durring a mass write cycle: channel 1 is MOSI, channel 2 is MISO, channel 3 is SCK
SPI comm.jpg

Jaime
 

danadak

Joined Mar 10, 2018
4,057
Just an FYI. This is a mature technology with Cypress, but not quite as capable in
some aspects, more in others.

ADC 1 20 bit DelSig and 2 12 bit SAR
DAC V or I, 8 bits, can be dithered to 12 bits
ARM M0 or M3 core or dual core, 1 M0 and 1 M4 core
OpAmps, Analog Mux, Mixer, PGA, S/H, Comparator, Wavegen
Vref
HW Digital and Analog peripherals routable on and off chip, like FPGA
COM, BLE, BT, WiFi, SPI, UART, OneWire, I2C......
Custom using Verilog or Drag and Drop Schematic
PWM, Counter, Timer, Quadec, SR, LUT, flops and gates, glitch, debounce, comparator, edge, DMA, LCD.....

A list of components attached. A component is an on chip resource.

An example of filter using all onboard including DSP engine

upload_2018-12-15_14-59-21.png

Basic board with debug $ 15, and other boards. Compiler and IDE free.

Wavedac component - http://www.cypress.com/documentation/application-notes/an69133-psoc-3-psoc-5lp-easy-waveform-generation-wavedac8-component


Regards, Dana.
 

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Thread Starter

Jaime Fischer

Joined Dec 15, 2018
3
+

Thank you for your time to consider this post danadak.
Generating a sine wave to drive the primary is pretty strait forward.
An example to drive and condition an LVDT is:
https://www.analog.com/media/en/technical-documentation/data-sheets/ad598.pdf
It is a good solution to drive and decode an LVDT on a single chip, but the output is analog.
Producing a solution with multiple chips and passive components on a carefully designed circuit board is beyond my ability at this time.
There are many solutions for each requirement to drive, condition, and digitize an LVDT, but I have not found a single chip solution until now.
The TI product has all of the devices including an ARM=Cortex M0 MCU on one very small chip.
I have been waiting for this solution for a while, to bad I can not get it to work for me.
Best Regards
Jaime
 

danadak

Joined Mar 10, 2018
4,057
The PSOC is not multiple chips, its one chip with many peripherals, analog, resources,
memory, like the SOC. It comes in several families -

PSOC 4 low end M0 (No DSP, or DelSig, SAR ONLY)
PSOC5LP High end M3
PSOC 6 Dual Core M0 + M4

Regards, Dana
 

Thread Starter

Jaime Fischer

Joined Dec 15, 2018
3
The PSOC is not multiple chips, its one chip with many peripherals, analog, resources,
memory, like the SOC. It comes in several families -

PSOC 4 low end M0 (No DSP, or DelSig, SAR ONLY)
PSOC5LP High end M3
PSOC 6 Dual Core M0 + M4

Regards, Dana
Dana
I want you to know that your thoughts and time have value to me and you words have not fallen on deaf ears (so to speak)
The device you have mentioned is a great solution for many applications including this one.
I was not familiar with the CYPRESS MCU, after looking at the product may be considered as a learning tool for me.
My issue is the lack of experience coding microcontrollers.
I am very excited about development boards I have purchased from different manufacturers, mostly from Microchip, along with several versions of their 8-Bit MCUs.
The MPLAB IDE along with the PICKit-3 seem to be a great tool for learning how to code microcontrollers.
I have a long way to go before I will have the skill required to program complex applications like you have described.
The PGA970 is specifically designed to be used with LVDT devices requiring very little or no coding, potentially a good fit for my level of skill.
The problem I have along with other individuals, we can not get it to operate.

best regards
Jaime
 
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