PaperS3 revisions - details needed
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I've finally got myself a handful of PaperS3 units to use around my home for display purposes, and to tinker around with.
Unfortunately, M5 doesn't seem keen on publishing the actual revision details, which has led to a few issues.
V1.0 had QC charging issues, and this model has published schematics.
V1.1 and V1.2 are unclear revisions that fix this charger issue. The back print also changed to now include a "5V ONLY" warning on the USB port. However, schematics are not available at this point, nor is there an actual changelog.
The first issue that is quite apparent to me, is related to the USB_DET line. Based on the 1.0 schematics, USB_DET is connected to the 5V USB line, via a simple 5.1k/5.1k voltage divider. This should result in a 2.5V readout, and based on code samples (written for the 1.0 revision), a simple multiplication by 2.0 should give the actual USB voltage.
Well, on my V1.2 units, the raw readout is 0.280-0.299V (0.283-0.285 with a 5.03-5.04V input, 0.290-0.97 with a 5.18-5.20V input, verified with a USB-C power monitor). This requires a weird, 16.3-16.7V multiplier depending on the voltage, to get 1/100 precision (multiplier gets lower as voltage grows).
I know it's a minor issue, but still, the fact that there are such undocumented changes, is quite annoying.
Could we please get the V1.1 and V1.2 schematics and actual itemised changelog released please?