# Tools

## usb_update.py

`usb_update.py` is the script for copying firmware packages from a host onto a Precursor device.

### Installation: Linux (Ubuntu/Debian)

* `sudo pip3 install pyusb progressbar2` (you need `pyusb` and `progressbar2` in the sudo environment)
* you probably need to run as `sudo`: `sudo ./usb_update.py [args]` to access the USB port; add the appropriate command line arguments

In order to get `xtask` to work (it calls `usb_update.py`) you will need to add a udev rule to eliminate the need for sudo privs. Under Ubuntu 18.04LTS, it looks something like this:

1. Add a file called `99-precursor-usb.rules` to /etc/udev/rules.d/ with the following content as a single line terminated by a carriage return:
`SUBSYSTEM=="usb", ATTRS{idVendor}=="1209", ATTRS{idProduct}=="5bf0", GROUP="plugdev", TAG+="uaccess"`
2. Run `sudo udevadm control --reload-rules`
3. If the device was plugged in, you'll have to unplug it and plug it back in again for the new rules
to take effect.

We would appreciate any improvements/suggestions for alternate Linux distros. `udev` rules seem very distro-specific and change with time.

### Installation: Windows 10

* You will need to install python3 from the Windows App store if you don't already have it
* Run `pip3 install pyusb progressbar2` from a Powershell
* use [zadig](https://zadig.akeo.ie/) to remap `Precursor pvt2`'s Windows driver to `libusb-win32`
* Run `python3 .\usb_update.py [args]` from a Powershell; elevated privs are not necessary after using `zadig`.

Users have reported trouble navigating the Zadig UI. Here is a guide:

![zadig screenshot](zadig.png)

1. Select "Precursor pvt2" from the large pull-down box. Click the "Edit" checkbox if the menu is blank or unselectable.
1. Select the driver to be "libusb-win32", using the red highlighted arrows, as shown in the *right* text box. You can ignore the text in the left box.
1. Click the "Install Driver" (or "Reinstall driver") button (highlighted in green) once these settings are made. This step can take several minutes.

### Installation: iOS

We have no experience with iOS, nor do we own any modern Apple machines. In short, we have no idea
how to iOS.

I hear it's popular with the cool kids in Silicon Valley. If someone can contribute a guide that'd be great.

### Performance Note

Systems using an AMD Ryzen chipset run about 5x
slower than others (e.g. Raspberry Pi, Intel chipsets). This holds true across Linux/Windows OS. The
effect has been confirmed on both B450 and B550 Socket AM4 motherboards. It seems to be linked with
full-speed packet rates being throttled on AMD motherboards by the chipset, but TBD. Write speed is
~8.5kiB/s on AMD, vs ~44kiB/s on Raspberry Pi.

### Usage

`usb_update.py` works with Precursor devices that have Xous 0.8 or 0.9. Later releases may work,
but check the release notes.

The updater encodes the offsets of every binary location in the script. When these locations shift,
then the updater script should no longer be used for a given Precursor revision.

```
usage: usb_update.py [-h] [-s [SoC gateware file]] [-l [loader file]] [-k [kernel file]] [-e [EC gateware package]] [-w [WF200 firmware package]] [--audiotest [Test audio clip]] [--peek ADDR] [--poke ADDR DATA] [--check-poke]
                     [--config] [-i IMAGEFILE ADDR] [-n] [-f] [--bounce]

Update/upload to a Precursor device running Xous 0.8/0.9

optional arguments:
  -h, --help            show this help message and exit
  -s [SoC gateware file], --soc [SoC gateware file]
                        SoC gateware
  -l [loader file], --loader [loader file]
                        Loader
  -k [kernel file], --kernel [kernel file]
                        Kernel
  -e [EC gateware package], --ec [EC gateware package]
                        EC gateware
  -w [WF200 firmware package], --wf200 [WF200 firmware package]
                        WF200 firmware
  --audiotest [Test audio clip]
                        Test audio clip (must be 8kHz WAV)
  --peek ADDR           Inspect an address
  --poke ADDR DATA      Write to an address
  --check-poke          Read data before and after the poke
  --config              Print the descriptor
  -i IMAGEFILE ADDR, --image IMAGEFILE ADDR
                        Manually specify an image and address. Offset is relative to bottom of flash.
  -n, --no-verify       Skip readback verification (may be necessary for large files to avoid WDT timeout). Only honored with -i.
  -f, --force           Ignore gitrev version on SoC and try to burn an image anyways
  --bounce              cycle the device through a reset
```

You can try reading the first word out of the ROM to see if `usb_update.py` is working correctly.
It's located at 0x20000008, and it's always `0x665599aa` (this is the Xilinx FPGA bitstream sync word),
as follows:

```
% python3 ./usb_update.py --peek 0x20000008
0x665599aa
```