[development tutorial 5] crazy shell arm function mobile phone serial port experiment tutorial

ARM Feature phone
—— Crazy shell · Development board series
Serial port experiment tutorial

chart 1

Section 1 serial port hardware circuit

Serial port through USB Mouth and bracelet download debugging line lead out , Connect MCU Of P12 And P13 Pin , As shown in the figure below ：

chart 2

In the second quarter UART register

2.1 UART Introduce
    This UART Meet industry standards 16550, And it can communicate with peripheral devices in serial . Main equipment （CPU） adopt APB The bus writes data into UART And it is converted into serial format and sent to the target device . Serial data can also be accessed through UART After being received and stored , The master device reads the received data .
UART Module not supported DMA, But it has an interior FIFOs, And support hardware flow control signals （RTS,CTS,DTR,DSR）.
UART Module has 16 Byte sending and receiving FIFO; Support hardware flow control （CTS/RTS）; Shadow register to reduce software overhead and programmable software reset ; Send interrupt mode with empty register ;IrDA 1.0 SIR Mode supports low power consumption mode ; Programmable byte attributes 、 Check bit and stop bit （1,1.5,2）; It can disconnect the communication and detect whether the communication line is disconnected ; Identification of interrupt priority ; Programmable serial communication baud rate .
2.2 UART register
UART There are many related registers , So we only introduce the commonly used registers , For others, please refer to the official data manual DA14580_DS_v3.1.pdf, Located in the directory ：..\WT Development board \ Hardware information .
2.2.1 Receive buffer register

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15:8 position ： Keep unused ;
7:0 position ： Receive buffer register .
2.2.2 Interrupt enable register

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15:8 position ： Keep unused ;
7 position ： Send the air interrupt enable bit ;
6:4 position ： Keep unused ;
3 position ： Modulation state interrupt enable bit ;
2 position ： Receive status interrupt enable bit ;
1 position ： Send end interrupt enable bit ;
0 position ： Data received enable bit .
2.2.3 Interrupt identification register /FIFO Control register

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15:0 position ： Write as FIFO Control register , Read is interrupt identification register .
2.2.4 Communication line control register

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15:8 position ： Keep unused ;
7 position ： Baud rate enable bit ;
6 position ： Stop control bit ;
5 position ： Keep unused ;
4 position ： Parity select bit ;
3 position ： Check bit ;
2 position ： Stop bit ;
1:0 position ： Data length .
2.2.5 Modulator control register

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15:7 position ： Keep unused ;
6 position ： Infrared communication enable bit ;
5 position ： Automatic flow control enable bit ;
4 position ： Loop position , Used for testing ;
3 position ： User specified output 2;
2 position ： User specified output 1;
1 position ： Send a request ;
0 position ： Keep unused .
2.2.6 Communication line status register

chart 8
15:8 position ： Keep unused ;
7 position ： receive FIFO Error bit ;
6 position ： Transmitter vacancy ;
5 position ： Send hold register empty ;
4 position ： Abnormal stop in broken position ;
3 position ： Frame error bit ;
2 position ： Check the error bit ;
1 position ： Overflow error bit ;
0 position ： Data ready bits .
2.3 Explanation of register configuration
#define CLK_PER_REG                 (* ( volatile uint16*)0x50000004)
#define UART_RBR_THR_DLL_REG        (* ( volatile uint16*)0x50001000)
#define UART_IER_DLH_REG            (* ( volatile uint16*)0x50001004)
#define UART_IIR_FCR_REG             (* ( volatile uint16*)0x50001008)
#define UART_LCR_REG                (* ( volatile uint16*)0x5000100C)
#define UART_MCR_REG               (* ( volatile uint16*)0x50001010)
#define UART_LSR_REG                (* ( volatile uint16*)0x50001014)
#define UART_MSR_REG               (* ( volatile uint16*)0x50001018)
#define UART_SCR_REG                (* ( volatile uint16*)0x5000101C)
start-up UART1 Module clock CLK_PER_REG |= 0x0080;
Serial port initialization register configuration ：
First enable baud rate configuration UART_LCR_REG = 0X08;
Configure baud rate UART_IER_DLH_REG = 0; UART_RBR_THR_DLL_REG = 9;
8 Bit data , No verification ,1 Bit stop bit UART_LCR_REG = 0X03;
Turn off the infrared communication function UART_MCR_REG = 0X00;
Can make FIFO, UART_IIR_FCR_REG = 0X01;
Turn off interrupt UART_IER_DLH_REG = 0X00;
Receive a byte , Wait for reception to complete while((UART_LSR_REG&0x01)==0); Read received data rx_data = UART_RBR_THR_DLL_REG;
Send a byte 0x55, Waiting to send is empty while((UART_LSR_REG&0x20)==0); Fill in the sending data UART_RBR_THR_DLL_REG = 0xaa;

In the third quarter UART experiment
The modules used in the experiment are ： Bottom plate of mobile phone development board ,Jlink Debugging tools ,USB Conversion module 、 DuPont line 、3.7V Lithium battery or Mocro USB Line .
Use USB The serial transfer module is connected to the Bluetooth serial port of the mobile phone , The connection is as follows ：
    (1)USB One end of the transfer module only needs to be connected with DuPont line RXD、TXD、GND Three pins , As shown in the figure below ：

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 (2) One end of the main control backplane of the mobile phone needs to use DuPont cable to connect to the left J7 Three pins , And USB The pins of the conversion module correspond one by one （ Serial port pins cross ）, Respectively RXD-->TXD、TXD-->RXD、GND-->GND, As shown in the figure below ：

chart 10
Use JLINK Connect your mobile phone with Bluetooth via DuPont cable , The connection is as follows ：
(1)JLINK One end only needs to be connected with DuPont wire JLINK Of SWC、SWD、GND Three pins , As shown in the figure below ：

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(2) The Bluetooth end of the mobile phone needs to use DuPont cable to connect the upper right J3 Three pins , And JLINK The connecting pins of the correspond one by one , Respectively SWC-->SWCLK、SWD-->SWDIO、GND-->GND, As shown in the figure below ：

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take JLINK Plug in the computer USB Interface , After connecting, power the main control board of the mobile phone , For detailed introduction, please refer to 《 How to power on 》 course , Path is ：..\WT_Mobile\0. So let's start here \0. Power on test .
Open serial port experiment Keil engineering uart.uvproj, Located in the directory ：..\WT_Mobile\1. Junior course \DA14580\2_ primary _ A serial port \projects\target_apps\peripheral_examples\uart\Keil_5, As shown in the figure below ：

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Open the serial port debugging assistant to connect the serial port , The baud rate is 115200. stay KEIL in , Compile code , Click on DEBUG, Then click Run at full speed , You can see the information printed by the serial port debugging assistant , Return whatever you send , For example, send “WT Mobile Test!” It will return “WT Mobile Test!”, As shown in the figure below ：

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