| openpowerbot | [slack] <Matt Johnston> lkcl: dfu-util with an orangecrab 0.2.1 85f | 05:48 |
|---|---|---|
| lkcl | Matt: hmm. i wonder if it's down to the fact that USB connects directly to the ECP5? | 10:33 |
| lkcl | the fact that there's an external pull-up resistor (1.5k) tells me that the ECP5 itself may actually be doing a form of bit-banging USB 1.1 | 10:34 |
| lkcl | i.e. totally unsophisticated | 10:34 |
| lkcl | consequently if you try to connect it to "modern" devices, it's hit-and-miss | 10:35 |
| lkcl | Lattice probably *cough* know this and always connect to it via a known-good, known-tested IC such as on-board FT232s which have a more reliable (mass-volume-tested) USB interface | 10:36 |
| lkcl | like on the VERSA_ECP5 and the ULX3S | 10:36 |
| openpowerbot | [slack] <Matt Johnston> mm not sure how valentyusb works. https://github.com/gregdavill/foboot/blob/OrangeCrab/hw/foboot-bitstream.py is the bootloader | 10:36 |
| lkcl | Matt: check the schematics. | 10:37 |
| lkcl | https://libre-soc.org/irclog-microwatt/%23microwatt.2021-09-25.log.html#t2021-09-25T18:42:07 | 10:38 |
| lkcl | page 2 Quadrant 3D - the incoming USB cable is connected *DIRECTLY* to the ECP5, pads PR44C and PR47D | 10:38 |
| lkcl | whereas for the VERSA_ECP5 the incoming USB cable is connected to a (reliable) FT2232 ASIC | 10:39 |
| * lkcl checking that foboot source code | 10:40 | |
| lkcl | https://github.com/im-tomu/valentyusb | 10:41 |
| lkcl | USB "Full Speed" | 10:41 |
| lkcl | that means it's effectively barely above "bit-banging" | 10:41 |
| lkcl | USB 1.1 | 10:42 |
| lkcl | 12 mbits per second | 10:42 |
| lkcl | it requires no complexity of any kind | 10:42 |
| lkcl | no analog I/O | 10:42 |
| lkcl | just a single external 1.5 kOhm resistor on one of the wires. | 10:42 |
| lkcl | exactly which you can see on Page 5 of Rev 20.2.1 Orange Crab Schematis, Quadrant A/B-2 | 10:43 |
| lkcl | by the time you get to USB 2.0 (480 mbits per second) you need an Analog PHY. USB 1.1 you can get away with standard digital I/O | 10:45 |
| lkcl | both valentyusb *and the Lattice ECP5 itself* appear to be critically relying on that fact | 10:45 |
| lkcl | bottom line that's not going to be reliable | 10:45 |
| lkcl | i'd recommend hunting around for older USB 2 Hubs, connecting them in between. | 10:46 |
| lkcl | exactly like how some people have already discovered, "strangely, my orangecrab seems to work if i connect it via a USB2 hub" | 10:47 |
| openpowerbot | [slack] <mithro> Did people ever see https://antmicro.github.io/embench-tester/ and https://antmicro.com/blog/2020/09/automatic-cpu-testing-with-embench/ ? | 21:36 |
| openpowerbot | [slack] <mithro> @Paul Mackerras -^ | 21:37 |
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