External Flashing
External flashing is required when switching from the original OEM firmware to coreboot firmware. Once a system is running coreboot, it can be updated internally using flashrom.
SOIC-8 and DIP-8 Flash Chips
The orientation the flash chip can be determined by identifying the circle near pin 1 (SOIC-8, soldered) or the semicircle at the top of the chip (DIP-8, socketed). Before removing DIP-8 flash chips, be sure to note the original orientation on the motherboard to ensure correct reinstallation.
CH341a
DIP-8 flash chips can be inserted into the CH341a for flashing, as depicted above.
SOIC-8 flash chips can be attached to the CH341a using a clip. In the above image, the line for pin 1 is colored red to facilitate quick orientation of the flash clip onto the motherboard.
Flashrom Support
The CH341a is supported by flashrom.
# read the flash chip flashrom -p ch341a_spi -r image.rom # write to the flash chip flashrom -p ch341a_spi -w image.rom
Voltage Verification
Many different USB flashers are sold as "CH341a", often without any specific product identifiers in the name besides "CH341a". Some flash tools using the CH341a supply the incorrect voltage, often 5.0V, to the data lines (pins 1, 2, 3, 5, 6, and 7) instead of 3.3V. A voltmeter can be used to test your specific CH341a variant. To measure the voltage at each pin, hold the voltmeter's ground to pin 4 (GND) and touch the probe to each of the other pins on the CH341a. In the image above, the red probe is connected to pin 8 (VCC) and the black probe is connected to pin 4 (GND). If they all ready ~3.3V, your CH341a was designed correctly. It is possible to fix a faulty CH341a, but this requires soldering.
Voltage Verified Programmers
| Type | Product Name | Product URL | Opearting Voltage | Remarks | Tested By |
|---|---|---|---|---|---|
| CH341a | CH341A V1.7 by liyf | https://www.amazon.com/dp/B0D9XQ4YBV | 3.35 ± 0.01 V | Has a switch for 1.8V, 2.5V, 3.3V, and 5V | mrothfuss |
| CH341a | Unbranded CH341A (blue) | https://www.aliexpress.us/item/2255800921201231.html | 3.32 ± 0.01 V | mrothfuss | |
| CH341a | Modded CH341A (black) | https://www.amazon.com/dp/B07R5LPTYM | 3.30 ± 0.01 V | Modded to operate at 3.3V instead of 5V | mrothfuss |
| CH341a | Unbranded CH341A (blue) | https://www.amazon.com/dp/B082KMN5D9 | N/A | Dead on Arrival | mrothfuss |
| CH347 | Unbranded CH347 | https://www.aliexpress.us/item/3256805429430879.html | 3.26 ± 0.01 V | More reliable than the CH341a | mrothfuss |