Quote from elmor on 2023-07-09, 21:40

Quote from shawn on 2023-06-29, 00:53

Quote from elmor on 2023-05-10, 11:19

Quote from shawn on 2023-05-10, 06:19

Hi Jon,

I would like to double check - is the register latching scheme for I2C 0x8X / 0x9X implemented in the latest shipping version of PMD-USB FW? We are considering to order several more units shortly and for a few reasons (mainly because we have already tested + validated the I2C interface), we still prefer the I2C interface rather than USB. Thanks.

Edit: Looking at the datasheet closer, I should have asked this question first: does the PMD-USB still support an I2C interface?

Hello Shawn,

The register latching is different for PMD-USB, much due to your feedback. Values are copied to a second buffer for sending over USB after an ADC update to prevent the above issue. Additionally there's a bootloader that allows for firmware updates on PMD-USB, meaning it's easier to patch this type of bug going forward.

Regarding the I2C interface, the PMD-USB does not support it by default. Depending on how important it is, I see two ways PMD-USB could be customized to support it. It would require flashing a modified version of the PMD firmware on it through the PMD-USB bootloader. Then the I2C interface could either be exposed using the OLED header (and lose OLED support) or you could remove the CH340N USB-to-Serial IC and solder the I2C wires directly to those pads (UART TX/RX pins are the same a previous SDA/SCL pins). The MCU used is the same except with double the flash memory meaning it's code compatible. If this would be a viable solution I can prototype it for you.

Hi Jon,

Thanks for the info.

We have been testing the PMD-USB and unfortunately the USB latency is a problem for our application. But, we are very excited about the improved error margin / tolerances. Is it possible to get modified firmware for PMD-USB that supports the I2C interface through the OLED header (and lose OLED support)?

Thanks,

Shawn

Hi Shawn, can you make a support ticket for this and we'll continue over email? It'll be more efficient. Thanks!

/Jon

Quote from shawn on 2023-08-17, 03:01

Thank you for providing the custom FW. We were able to flash our PMD-USB units and confirm expected functionality.

Quote from kstyner on 2023-09-18, 08:36

Hi Jon,

I found that there was on-going discussion on sampling rate of your previous revision.

From my understanding, current revision is connected with PC via USB to serial interface. Which means PMD device will communicate with USB-serial converter with UART interface and will have 115200 baud rate.

Isn't it a degrade in sampling rate stands point?

Please correct me if I', wrong.

 

Thanks

Jason