Hi everyone, is there any technical documentation for the spec of the caravel GPIOs pads? We are ass...

Ellen Wood

11/04/2023, 5:34 PM

Hi everyone, is there any technical documentation for the spec of the caravel GPIOs pads? We are assuming they are all level shifted up to 3.3v, is that correct? It would be nice for the future to simultaneously have 1.8v and 3.3v pads. It looks like the pad itself is capable of doing this from the skywater spice model, is this true? Is there a spec on the output (how many miliamps it can drive etc)?

☝️ 1

Tim Edwards

11/04/2023, 8:07 PM

All of the information about the I/Os can be found here: https://skywater-pdk.readthedocs.io/en/main/contents/libraries/sky130_fd_io/docs/user_guide.html (for SkyWater; the GF documentation is elsewhere).

Tim Edwards

11/04/2023, 8:09 PM

But the short answer is that yes, all pad-connected signals are 1.8V on the core side and 3.3V on the pad side, with level shifters in between. There is a 3.3V core side signal in_h which is just the signal in tapped before the level shifter. There is no equivalent 3.3V core-side output.

Ellen Wood

11/05/2023, 8:39 AM

Thank you 🙂 I found this while digging around too, putting it here incase it helps anyone else: https://caravel-harness.readthedocs.io/en/latest/supplementary-figures.html

2 Views

Open in Slack

Previous Next

What is Linen?

Linen is a search-engine friendly community platform. We offer integrations with existing Slack/Discord communities and make those conversations Google-searchable.