Complete technical text from Chinese RK-KF-YF-90 V1.2.0, pages 5–7. The source product table says all, with RT-Thread lts-v3.1.x/master and lts-v4.1.x/master; example paths use rockchip-pisces. “All” does not confirm support for every ArmSoM board. Platform reference: verify SoC/BSP, UART pins, voltage, clock tree and console ownership. This is not a Linux serial-driver guide. Only a Chinese source exists, with no standalone figures; all code is retained in four languages. No serial or hardware tests were run.
The source configuration selects UART0 and UART2, while list_device lists uart0–uart7. These are separate examples, not proof that one configuration creates every device. Both the 4M/optional 8M limit and the need to test above 1.5M are retained; the source does not specify the exact 1.5M boundary.
1. Rockchip UART features
UART (Universal Asynchronous Receiver/Transmitter):
- Compatible with 16550A.
- Some ports support automatic hardware flow control; others do not. Consult the datasheet.
- Interrupt and DMA transfer modes.
- Up to 4M baud; some support 8M. Consult the datasheet.
- Some chips support hardware RS485; consult the datasheet.
2. Software
2.1 Source paths
Serial framework: serial.c is the device driver; posix_termios.c provides configuration similar to Linux tty.
components/drivers/include/drivers/serial.h
components/drivers/serial/serial.c 设备驱动
components/libc/termios/posix_termios.c 类似linux的tty配置
components/libc/termios/posix_termios.h
Serial-driver adaptation layer:
bsp/rockchip-pisces/drivers/drv_uart.c
bsp/rockchip-pisces/drivers/drv_uart.h
Serial test commands: user applications can follow this driver example.
bsp/rockchip-common/tests/termios_test.c
2.2 Configuration
Enable the serial-port configuration; /dev/uart0..9 devices are generated.
RT-Thread rockchip RKxxxx drivers --->
[*] Enable UART
[*] Enable UART0
[ ] Enable UART1
[*] Enable UART2
[ ] Enable UART3
[ ] Enable UART4
[ ] Enable UART5
[ ] Enable UART6
[ ] Enable UART7
[ ] Enable UART8
[ ] Enable UART9
List the generated serial devices with:
msh >list_device
device type ref count
------ -------------------- ----------
uart7 Character Device 0
uart6 Character Device 0
uart5 Character Device 0
uart4 Character Device 2
uart3 Character Device 0
uart2 Character Device 0
uart1 Character Device 0
uart0 Character Device 0
2.3 Serial-port tests
Enable the serial test program:
lts-v3.1.x:
RT-Thread Components --->
Device virtual file system --->
[*] Using device virtual file system
-*- Using devfs for device objects
POSIX layer and C standard library --->
[*] Enable termios feature
RT-Thread bsp test case --->
RT-Thread Common Test case --->
[*] Enable BSP Common TEST
[*] Enable BSP Common UART TEST
lts-v4.1.x:
RT-Thread Components --->
[*] DFS: device virtual file system --->
[*] Using devfs for device objects
C/C++ and POSIX layer --->
POSIX (Portable Operating System Interface) layer --->
[*] Enable POSIX file system and I/O
[*] Enable I/O Multiplexing select() <sys/select.h>
[*] Enable Terminal I/O <termios.h>
RT-Thread bsp test case --->
RT-Thread Common Test case --->
[*] Enable BSP Common TEST
[*] Enable BSP Common UART TEST
Test commands for receiving, sending, receiving then sending, and external loopback:
receive data:
termtest r /dev/uart4 115200
send data:
termtest s /dev/uart4 115200
receive then send:
termtest t /dev/uart4 115200
externel loopback:
termtest l /dev/uart4 115200
2.4 Baud-rate support
The source states that rates below 1.5M are supported. Rates above 1.5M require actual testing because support depends on the CLK clock tree.
2.5 Console configuration
RT-Thread Kernel --->
Kernel Device Object --->
[*] Using console for rt_kprintf
(128) the buffer size for console log printf
(uart2) the device name for console