I have a fairly new JTAG Pod, it has four UART (TX,RX, GND, Vref) and eight JTAG (POR, TDO,SRST,TDI,TMS,TCK,GND,VCC) pins. How does this compare with the JTAG/UART Pod that I see in photos with three UART and seven JTAG pins? Also, what's the compatibility between Ultra96-V1 and Ultra96-V2 with both Pods?
Either Pod is compatible with either Ultra96-V1 or V2. The differences is in the potential features that you get. I can explain what we were thinking when we designed the JTAG/UART Pod in the summer of 2018.
JTAG – addition of the POR pin (Pin #8)
- This is not a requirement for JTAG to work. Ultra96-V1 did not expose this pin. Ultra96-V2 does. Having POR allows certain debuggers one additional level of control for remote debugging when the hardware isn’t available. If the hardware gets completely hung, then the debugger can toggle POR to force a reboot.
UART – addition of the VREF pin (Pin #4)
- VREF allows the option for level translating between the 3.3V signaling on the Pod and whatever is on the host. This was NOT necessary on either Ultra96-V1 or Ultra96-V2 since both have on-board level translation that already put the signaling on the UART header at 3.3V. This was really a future-looking move thinking we might want to use this pod with some other board in the future that didn’t have level translation.
- If you want to use the level translation, then it requires the user to move the JT1 resistor jumper to the other position. JT1 is located on the backside of the Pod in the corner by the 4-pin UART socket as shown in the photo below.
When we first built the JTAG/UART pod, we only had Ultra96-V1 at our disposal. Therefore, we didn’t have a way to test the UART-VREF and JTAG-POR functions. We built the first batch of pods with only the 3- and 7- pin connectors, matching what was available on Ultra96-V1. After we had first prototypes of Ultra96-V2, we were able to validate the UART-VREF and JTAG-POR features. Pod builds after that (summer 2019) were built with 4- and 8-pin connectors.
To be clear, all of these combinations work:
- Ultra96-V1 with 3/7 Pod – The Pod doesn't populate the 4th or 8th sockets so the 3/7 alignment of the Pod exactly aligns with the Ultra96-V1
- Ultra96-V1 with 4/8 Pod – the Pod’s 4th and 8th sockets extend beyond the V1’s 3/7 pins without harm. UART VREF is not used due to default position of JT1. JTAG-POR is not functional.
- Ultra96-V2 with 3/7 Pod – The V2’s 4th and 8th pins are not connected. UART VREF is not used due to default position of JT1. JTAG-POR is not functional.
- Ultra96-V2 with 4/8 Pod – Everything aligns. UART VREF is not used due to default position of JT1. JTAG-POR is functional, assuming the debugger supports it.
- 4/8 Pod with some other board – the Pod is self-powered, so theoretically the Pod will work with any other board. You need 2mm wire connectors on the Pod side (not 0.1”). If you want the UART VREF capability, you need to move the JT1 jumper to the opposite position.
If you are interested in purchasing Ultra96-V2, the JTAG/UART Pod, or other Ultra96-V2 accessories, please use the links below.
|Buy Ultra96-V2Buy Ultra96-V2|
|Buy Ultra96-V2 I-gradeBuy Ultra96-V2 I-grade|
|Buy Ultra96-V2 4A Power SupplyBuy Ultra96-V2 4A Power Supply|
|Buy Ultra96-V2 JTAG/UART PodBuy Ultra96-V2 JTAG/UART Pod|