Difference between revisions of "How to use UART RK3568"
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= '''Boards''' = | = '''Boards''' = | ||
| − | == | + | == RSB-4810 Borad == |
{| border="1" cellspacing="1" cellpadding="1" | {| border="1" cellspacing="1" cellpadding="1" | ||
| Line 47: | Line 47: | ||
| + | '''Note : ''' | ||
| + | 1. Only USB2COM2 and USB2COM3 support RS485 mode. | ||
| + | 2. COM2 is designed as debug port default. | ||
| + | == ROM-5880 Borad == | ||
| − | + | {| border="1" cellspacing="1" cellpadding="1" | |
| + | |- | ||
| + | | '''COM Name''' | ||
| + | | '''Device Node''' | ||
| + | | '''Remark''' | ||
| + | |- | ||
| + | | COM1<br/> | ||
| + | | /dev/ttyS4<br/> | ||
| + | | support RS232, no flow control<br/> | ||
| + | |- | ||
| + | | COM2<br/> | ||
| + | | /dev/ttyS7<br/> | ||
| + | | support RS232, no flow control<br/> | ||
| + | |- | ||
| + | | COM3<br/> | ||
| + | | /dev/ttyUSB2<br/> | ||
| + | | support RS232 and RS485<br/> | ||
| + | |- | ||
| + | | COM4 | ||
| + | | /dev/ttyUSB3<br/> | ||
| + | | support RS232 and RS485<br/> | ||
| + | |- | ||
| + | | COM5<br/> | ||
| + | | /dev/ttyUSB0 | ||
| + | | support RS232 | ||
| + | |- | ||
| + | | COM6<br/> | ||
| + | | /dev/ttyUSB1<br/> | ||
| + | | support RS232<br/> | ||
| + | |} | ||
'''Note : ''' | '''Note : ''' | ||
| − | 1. Only USB2COM2 and USB2COM3 support | + | 1. Only USB2COM2 and USB2COM3 support RS-485. |
2. COM2 is designed as debug port default. | 2. COM2 is designed as debug port default. | ||
Revision as of 02:30, 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/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 RS-485.
2. COM2 is designed as debug port default.
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).