Difference between revisions of "How to use UART for RK3399 RSB4710"
Yunjin.jiang (talk | contribs) (Created page with "= '''Overview''' = <font color="#000000">The Android/Linux UART/serial port access from user is through the tty-devices. The tty-devices have different names depending on UAR...") |
Yunjin.jiang (talk | contribs) |
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= How to config RS232 or RS485 mode = | = How to config RS232 or RS485 mode = | ||
| − | + | Enter U-boot interrupt mode | |
Connect device to debug port, and open debug console. See more : [http://ess-wiki.advantech.com.tw/view/How_to_debug_for_RK3399_RSB4710 How_to_debug]. | Connect device to debug port, and open debug console. See more : [http://ess-wiki.advantech.com.tw/view/How_to_debug_for_RK3399_RSB4710 How_to_debug]. | ||
| Line 78: | Line 78: | ||
== Config Uart Mode == | == Config Uart Mode == | ||
| − | <pre>setenv | + | |
| − | setenv | + | Only ttyUSB2 and ttyUSB3 support RS485 mode. |
| + | |||
| + | '''RS485 Mode: ''' | ||
| + | <pre>setenv uart_mode 0x0c | ||
| + | saveenv | ||
| + | reset | ||
| + | </pre> | ||
| + | |||
| + | '''RS232 Mode: ''' | ||
| + | <pre>setenv uart_mode 0x00 | ||
saveenv | saveenv | ||
reset | reset | ||
</pre> | </pre> | ||
| − | |||
| − | The default value is RS232. | + | |
| + | '''Note : ''' | ||
| + | |||
| + | The default value is RS232. | ||
| + | |||
| + | Cp210x support four port, but RSB4710 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 RSB485 mode, please change 0x0c to 0x04 (or 0x08). | ||
Revision as of 03:56, 9 March 2020
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
RSB4710 Borad
| COM Name | Device Node | Remark |
| COM0 | /dev/ttyS0 |
for BT Data |
| COM2 |
/dev/ttyS2 |
Debug Port |
| COM4 |
/dev/ttyS4 |
support RS232, no flow control |
| USB2COM0 |
/dev/ttyUSB0 |
support RS232 |
| USB2COM1 | /dev/ttyUSB1 |
support RS232 |
| USB2COM2 |
/dev/ttyUSB2 | support RS232 and RS485 |
| USB2COM3 |
dev/ttyUSB3 |
support RS232 and RS485 |
Note :
1. Only COM4、USB2COM0、USB2COM1、USB2COM2、USB2COM3 are designed for custom using.
2. Only USB2COM2 and USB2COM3 support RSB485.
3. 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 RSB4710 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 RSB485 mode, please change 0x0c to 0x04 (or 0x08).