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Denis 'GNUtoo' Carikli, 03/08/2020 04:03 AM
UART¶
There is an in-depth article covering several Samsung devices in the SamsungSerial page
Settings¶
Device and documentation | I/O voltage | ID<->GND | SOC TX | SOC RX | switch | stock bootloader settings | Comments |
---|---|---|---|---|---|---|---|
GT-I9100 | 510k9 | D- | D+ | MAX8997 | UART settings: ttySAC2 115200 8N1 To get the UART enabled at boot with the stock bootloader: * Power the phone off and remove the battery * Put a battery in * Hold the select button * Plug the UART * Release the select button |
At some point the boot procedure switches to the modem UART, it's probably some linux driver doing that | |
GT-N7000 | 510k9 | D- | D+ | UART settings: 115200 8N1 | |||
GT-I9100G_CHN_CHN | 1.8V8 ? | 619k9 | D- | D+ | ? | UART settings: 115200 8N1 | Very few prints from Xloader, the next bootloader used by Android 2.6.3 doesn't seem to print much |
GT-I9300 | 1.8V1 | 619 kOhms3 | D- | D+ | MAX776935 | UART settings: 115200 To increase verbosity during boot: * Power off the phone and remove the battery * Put a battery in * Press the hold the volume-down button * Plug the UART and wait for the first lines to be printed * Release the volume-down button |
It gives a shell once Replicant 6 has booted |
GT-I9305 | |||||||
GT-N7100 | ? | ||||||
GT-N7105 | ? | ||||||
Galaxy Nexus (GT-I9250) | 619 kOhms4 | D+ | D- | FSA94807 | UART settings: * By default: ttyFIQ0, 115200 8N1 * After patching Linux: ttyO2, 115200 8N1 See GalaxyNexusI9250SerialConsole for more details. |
||
Nexus S | 150 kOhm | FSA9480 | |||||
Optimus Black (P970) | 1.8V6 | N/A2 | DP3T | ||||
ODROID-U3, console UART | 1.8V | connector | UART settings: ttySAC1, 115200 8N1 | ||||
ODROID-U3, IO pins UART | 1.8V | connector | UART settings: ttySAC0, 115200 8N1 |
1 Measured between USB GND and USB VCC
2 Code is required to use the switch as you need to configure both the MUIC and DP3T switch
3 See The related driver source code
4 See the postmarketOS wiki page on Serial debugging
5 See the driver and the ifixit teardown
6 Reference: OptimusBlackSerial
7 See board-tuna-connector.c fsa9480.c in kernel_samsung_tuna
8 Works, as it was tested on the device. TODO: measure the voltage, as lower UART voltages often works with higher voltage levels.
9 Works, as it was tested on the device. TODO: look the official reference in the driver for it.
Datasheets¶
Interesting links¶
- There is a page on Serial debugging on the postmarketOS wiki that contains information for using the serial port for many smartphones models.
- mv-uart A serial port adapter with configurable voltages (and GPIOs)
- DHylands_SGS2_SerialAdapter : A very compact setup but with fixed resistor value.
See also¶
- BootloaderInterfaces: Documentation about the stock bootloaders interfaces
Updated by Denis 'GNUtoo' Carikli over 4 years ago · 69 revisions