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  over 2 years ago by clanig | Reply

  • Tried to attach official CH340G USB <-> Serial adapter and noticed that the adapter is only recognized by the kernel in 5V mode.
  • Did some diagnosis and found that the 3.3V mode might be broken because only 1.9V are measurable on the 3.3V circuit path.
  • According to the datasheet the CH340G requires VCC=[3.3, 3.8]V for 3.3V mode. Due to insufficient power supply the IC might not start and finally not be recognized by the kernel. Have contacted the manufacturer.
  • Since 3.3V mode is required to get a serial TTY connection, I will proceed (almost) blindly and try to prevent provoking debug necessities.

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- Tried to attach official CH340G USB <-> Serial adapter and noticed that the adapter is only recognized by the kernel in 5V mode. - Did some diagnosis and found that the 3.3V mode might be broken because only 1.9V are measurable on the 3.3V circuit path. - According to the datasheet the CH340G requires VCC=[3.3, 3.8]V for 3.3V mode. Due to insufficient power supply the IC might not start and finally not be recognized by the kernel. Have contacted the manufacturer. - Since 3.3V mode is required to get a serial TTY connection, I will proceed (almost) blindly and try to prevent provoking debug necessities.
 
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Reply to clanig
• Tried to attach official CH340G USB <-> Serial adapter and noticed that the adapter is only recognized by the kernel in 5V mode.
• Did some diagnosis and found that the 3.3V mode might be broken because only 1.9V are measurable on the 3.3V circuit path.
• According to the datasheet the CH340G requires VCC=[3.3, 3.8]V for 3.3V mode. Due to insufficient power supply the IC might not start and finally not be recognized by the kernel. Have contacted the manufacturer.
• Since 3.3V mode is required to get a serial TTY connection, I will proceed (almost) blindly and try to prevent provoking debug necessities.
---
# A First Level Header
## A Second Level Header

Use one asterisk to *emphasize*

Use two asterisks for **strong emphasis**

- Use hyphens
- for unordereed
- lists

This is an [link to example.com](http://example.com/)

This is an image ![an openSUSE geeko icon](https://en.opensuse.org/images/d/d0/Icon-distribution.png)

This is a user link @hans

This is a project link hw#some-cool-title
More Complex Markdown Help
Formatting Help
• Edit
• Preview