FTDI-LA
 | |
| Status | supported |
|---|---|
| Source code | ftdi-la |
| Channels | 8 |
| Samplerate | 10MHz |
| Samplerate (state) | — |
| Triggers | none (SW-only) |
| Min/max voltage | 0V — 5V |
| Memory | none |
| Compression | none |
| Price range | $2 - $27 |
There's a best-effort driver to acquire raw samples from any FTDI chip supporting bitbang modes. As these chips have tiny I/O buffers, it doesn't guarantee overrun-free operation so it may lose samples, yet moving the device to a separate USB host or lowering the sample rate helps.
Hardware
FT232RL and FT2232H are known to work, and adding an unsupported chip should be easy. Boards with the former are available on ebay for $3, but it doesn't support USB 2.0 hence sample rates will be lower. FT*H chips may provide ~20MHz sample rate over a reliable high speed USB link and (bursts of?) 60MHz using synchronous FIFO mode (not implemented in the sigrok driver).
Pitfalls
This driver currently only supports FTDI chips configured in bitbang mode. This means you cannot use the driver with a board where an EEPROM configures the FTDI device to operate in a different mode. This means the driver doesn't work with Bitscope devices, for example.
I've tried to use FT232RL to capture UART serial transmission and the timing was waaay off, so it didn't worked out even on low baudrates. Sometimes it seemed like the sample rate was half of announced value, sometimes it was completely off. This probably still needs lots of tweaking if you want to do some serious protocol decoding business. (Haven't tried the FT*H chips, they are supposed to work better)
Windows
On Windows, you'll need to assign the "WinUSB" driver to the device, otherwise the ftdi-la driver will not be able to find or use it.