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PGA309EVM-USB: USB DAQ Platform not communicating over ONE WIRE

Eric Etzell
Prodigy 10 points
Part Number: PGA309EVM-USB
Other Parts Discussed in Thread: PGA309

Tool/software:

Hello,

I am troubleshooting the One-Wire communications between my device and the USB DAQ platform. We are using a USB DAQ Platform board without the PGA309 Test board. Instead, we are plugging ONE_WIRE directly into our device, which is running a PGA309 chip with a 4k EEPROM. Our device's One-Wire is at 5V. 

We are then using PGA309 EVM Software to write and read the EEPROM table of the device connected to the USB DAQ Platform board. Specifically, we are using the 'EEPROM Table' tab, and the "Read Table" and "Load EEPROM From File" buttons. 

The issue seems to be that UART 1-wire communications are not making it from the uC all the way to the ONE_WIRE pin. 

 

I've looked at various points in the circuit using an O-scope and a brand-new USB DAQ Platform board. My findings are below:

 

Essentially:

- I see 3.3V and a UART signal coming out of the uC at TP26.

- Probing R35 there is no UART signal and the voltage reads 0 VDC.

- ONE_WIRE (to our device) shows 5 VDC (from our device) and no movement for UART. Interestingly, the current draw from our power supply (supplying power to our device) goes from ~2.3mA to ~4.4mA while the USB DAQ uC is transferring, even though there is no signal visible on ONE_WIRE.

- TP27 shows 0VDC, I don't really understand what drives the Disconnect One circuit but it seems like that should be powered during signal transfer and the 2-1 gate on U21 should be closed (on). Instead it is shorted to GND and the gate is open.

- TP25 and the Pull_Up signal are behaving the same way, it's grounded out and doesn't close the gate. 

- The gate of U21 and U13 measure OL, when the uC is sending UART communications and when it is not. 

- TP24, the uC Rx pin, shows 3.3VDC and no UART signal. 

- All active components (U21, U16, U13, U6) have proper voltages for both lower and upper rails. 

- All Jumpers are set to Default Jumper Settings for 5V, with the exception of Jump8 (I've tried both configurations, with the Speed-up circuit enabled and disabled.)

I'm thinking it's a setting in the software that allows us to control Disconnect_One and Pull_Up? It seems like the issue is that these two gates are not closing.

Any advice would be greatly appreciated!

Thank you,

Eric Etzell

  • 0
    TI__Mastermind 22172 points

    Hi Eric, 

    Thanks for posting on e2e!

    Your jumper configurations match mine in the board I use often in lab, I don't expect this is where the problem lies. What I imagine is happening is that the USB_DAQ is expecting a signal from the PGA309 Test board that your custom board is not providing. 

    I would be happy to debug with you, lets start with J3 and J4 of the USB DAQ board, the following are expected from Test board: 

    J1 mates with J3 in the USB board: 

    J2 mates with J4 in the USB board: 

    Here is where they are connected to on the PGA309 Test board: 

    On your EEPROM: 

    Pin 1 of the PGA309:

    Pin 7, 9, 12, 13, and 14 of the PGA309:

    A note on power supplies and ground, I would connect "VDUT" to the power supply of the PGA309 (pin 10 & 3). I would connect all grounds from the connector to the ground of your board... maybe its missing a ground return path and that's the reason the destruction to the board is occurring. 

    Please let me know if these connections are made and if you are still not getting the desired result.

    All the best,
    Carolina