Difference between revisions of "How to use UART RK3568"
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2. COM2 is designed as debug port default. | 2. COM2 is designed as debug port default. | ||
| − | + | <h2>ROM-5880 Borad</h2> | |
| − | + | <table border="1" cellpadding="1" cellspacing="1"> | |
| − | + | <tbody> | |
| − | + | <tr> | |
| − | + | <td><b>COM Name</b></td> | |
| − | + | <td><b>Device Node</b></td> | |
| − | + | <td><b>Remark</b></td> | |
| − | + | </tr> | |
| − | + | <tr> | |
| − | + | <td>COM1</td> | |
| − | + | <td>/dev/ttyS3</td> | |
| − | + | <td>support RS232,</td> | |
| − | + | </tr> | |
| − | + | <tr> | |
| − | + | <td>COM2</td> | |
| − | + | <td>/dev/ttyS7</td> | |
| − | + | <td>support RS232, no flow control</td> | |
| − | + | </tr> | |
| − | + | <tr> | |
| − | + | <td>COM3</td> | |
| − | + | <td>/dev/ttyS4</td> | |
| − | + | <td>support RS232</td> | |
| − | + | </tr> | |
| − | + | <tr> | |
| − | + | <td>COM4</td> | |
| − | + | <td>/dev/ttyS5</td> | |
| − | + | <td>support RS232, no flow control</td> | |
| − | + | </tr> | |
| − | + | </tbody> | |
| − | + | </table> | |
| − | |||
| + | <p><b>Note : </b></p> | ||
| − | + | <p> </p> | |
| − | |||
| − | |||
| − | |||
| − | |||
= How to config RS232 or RS485 mode = | = How to config RS232 or RS485 mode = | ||
Revision as of 02:40, 12 April 2023
Contents
Overview
The Android/Linux UART/serial port access from user is through the tty-devices. The tty-devices have different names depending on UART driver on different board.
RS-485
RS-485 uses half-duplex communication, which means that one medium is shared for transmitting and receiving data.
Therefore the system needs to control the RS-485 transceiver's transmit mode.
Usually the UART RTS signal is used to switch the transmitter on and off.
Boards
RSB-4810 Borad
| COM Name | Device Node | Remark |
| COM1 |
/dev/ttyS4 |
support RS232, no flow control |
| COM2 |
/dev/ttyS7 |
support RS232, no flow control |
| COM3 |
/dev/ttyUSB2 |
support RS232 and RS485 |
| COM4 | /dev/ttyUSB3 |
support RS232 and RS485 |
| COM5 |
/dev/ttyUSB0 | support RS232 |
| COM6 |
/dev/ttyUSB1 |
support RS232 |
Note :
1. Only USB2COM2 and USB2COM3 support RS485 mode.
2. COM2 is designed as debug port default.
ROM-5880 Borad
| COM Name | Device Node | Remark |
| COM1 | /dev/ttyS3 | support RS232, |
| COM2 | /dev/ttyS7 | support RS232, no flow control |
| COM3 | /dev/ttyS4 | support RS232 |
| COM4 | /dev/ttyS5 | support RS232, no flow control |
Note :
How to config RS232 or RS485 mode
Enter U-boot interrupt mode
Connect device to debug port, and open debug console. See more : How_to_debug.
Press "ctrl + c" key before power up the device, until get the following information on debug console :
Hit any key to stop autoboot: 0 => <INTERRUPT> =>
Then you can input the following cammand to config UART mode.
Config Uart Mode
Only ttyUSB2 and ttyUSB3 support RS485 mode.
RS485 Mode:
setenv uart_mode 0x0c saveenv reset
RS232 Mode:
setenv uart_mode 0x00 saveenv reset
Note :
The default value is RS232.
Cp210x support four port, but RSB4810 Only ttyUSB2 and ttyUSB3 support RS485 mode.
Above command "setenv uart_mode 0x0c", 0x0c means set bit2(ttyUSB2) and bit3(ttyUSB3) to 1 (0 means to RS232; 1 means to RS485).
If you just want ttyUSB2 (or ttyUSB3)to be RS485 mode, please change 0x0c to 0x04 (or 0x08).