: Transfer 10 MB of random data at 115200 baud, 8N1.
To see what baud rate the driver actually set:
But how well does it actually work on Linux? The answer, after years of a rocky history, is surprisingly well—thanks entirely to a robust, mainlined kernel driver that has matured into a model of stability and efficiency. linux ch340 driver
: For standard baud rates up to 115200, the CH340 is indistinguishable from premium chips. At 921600 baud, the CH340 starts showing occasional frame errors (about 0.1%), while the FTDI remains solid. But at 2Mbps, the CH340 surprises—it actually works, though with ~1% error rate. 4. The Driver in Action: Troubleshooting Common Issues Even with a mature driver, things go wrong. Here’s the practical guide. Issue: Device shows up as ttyCH341USB0 instead of ttyUSB0 Cause : You have the legacy ch341.ko driver loaded alongside the new one. Fix : Blacklist the old driver:
The next time you plug in that $5 Arduino Nano clone and dmesg cheerfully reports ch341-uart converter now attached to ttyUSB0 , take a moment to appreciate the layers of kernel engineering that made it work. The CH340 driver isn’t glamorous. But it gets the job done—quietly, reliably, and without complaint. Testing performed on Fedora 38 (kernel 6.4.15) and Raspberry Pi OS (kernel 6.1.21). All data available in the author’s GitHub repository. : Transfer 10 MB of random data at 115200 baud, 8N1
For professional or medical equipment? Probably not. The lack of guaranteed long-term supply, the chip’s weaker ESD protection, and the absence of manufacturer-provided Linux tools are real concerns.
sudo usermod -a -G dialout $USER # Log out and back in Cause : Power starvation. Many cheap CH340 boards draw power from the USB port’s 5V line and have inadequate decoupling. Fix : Use a powered USB hub or add a 100µF capacitor across VCC and GND on the device. Issue: Baud rate inaccuracies at 250000, 500000, or 1000000 Cause : The CH340’s internal clock (12 MHz or 48 MHz depending on variant) doesn’t divide evenly to these rates. Workaround : Use standard baud rates (9600, 19200, 38400, 57600, 115200, 230400, 460800, 921600). The driver will silently round non-standard rates to the nearest supported value. : For standard baud rates up to 115200,
| Metric | CH340 | FTDI FT232RL | |--------|-------|---------------| | Sustained throughput | 11.2 KB/s | 11.5 KB/s | | Max baud rate (stable) | 2 Mbps | 3 Mbps | | CPU usage @115200 | 0.8% | 0.7% | | Latency (worst-case) | 4 ms | 2 ms |