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[Development Tutorial 9] crazy shell arm function mobile phone-i2c tutorial

2022-07-26 16:49:00 【efans_ Mike】

ARM Feature phone
—— Crazy shell · Development board series
I2C course

chart 1

Section 1 I2C Hardware circuit
take P12 And P13 Configure to I2C Two interfaces of ,P12 And P13 It has been led out through the row needle , As shown in the figure below ：


chart 2



In the second quarter I2C

2.1 I2C Introduce
I2C Bus is a programmable control bus that provides support for circuit communication in the system , It is a software defined two-wire communication protocol .
Two lines I2C The serial interface includes a serial data line （SDA） And a serial clock line （SCL）;
Support two communication rates , The standard model （0~100Kb/s） And fast mode （ Less than or equal to 400Kb/s）;
Clock synchronization ;
32 Send and receive bytes FIFO;
Host send and receive operations ;
7 or 10 Bit address ,7 or 10 Send for mixed format ;
Block sending mode ;
The default slave address is 0x055;
Interrupt or poll operation mode ;
Programmable data line hold time ;

2.2 Register introduction
I2C There are many related registers , So we only introduce the commonly used registers , For others, please refer to the official data manual AD14580_DS_v3.1.pdf, Located in the directory ：..\WT Development board \ Hardware information .

2.2.1 I2C Control register


chart 3
15:7 position ： Keep unused ;
6 position ：I2C Slave enable bit ,’0’ Indicates that the slave device is enabled ,’1’ Indicates that the slave device is unavailable , This bit does not have to be set by software , But make sure that if this bit is ’0’ Then the... Of this register 0 It's also for ’0’;
5 position ： As the main equipment , Whether to send restart condition ,’0’ Indicates no ,’1’ Can be said ;
4 position ： As the main equipment , Decide to 7 Bit address or 10 Bit address starts sending ,’0’ Express 7 Bit address ,’1’ Express 10 Bit address ;
3 position ： As a slave device , Decide to 7 Bit address or 10 Bit address starts sending ,’0’ Express 7 Bit address ,’1’ Express 10 Bit address ;
2:1 position ：I2C Communication speed selection ,1 Indicates standard speed （100Kbit/s）,2 Express fast （400Kbit/s）;
0 position ：I2C Main equipment enable ,’0’ Indicates that the master device is unavailable ,’1’ Indicates that the master device is enabled , Make sure that if this bit is ’1’ Then the... Of this register 6 It's also for ’1’;

2.2.2 I2C Destination address register


chart 4
15:12 position ： Keep unused ;
11 position ： This bit determines whether the software broadcasts or starts byte commands ,’0’ It means to ignore the second 10 position GC_OR_START And normal use IC_TAR;
10 position ： If the first 11 Bit is set to ’1’, Then this bit indicates whether the controller broadcasts or starts byte commands ,’0’ Indicates the sending broadcast address , After that, you can only write , If a read operation is performed, it will result in TX_ABRT Set up , The controller stays in broadcast mode , Until the first 11 Bit is cleared ,’1’ Indicates the sending start byte ;
9:0 position ： This is the destination address sent by the master device , If the broadcast is sent, this bit is ignored ,CPU Just write these bits once ; Note that if the destination address is the same as the slave address, there is a loop , however FIFO Master slave sharing , So complete loop is feasible , Only one-way circuits are supported , A master device cannot send data to itself, but only to the slave device .

2.2.3 I2C Receive and send data cache and command register


chart 5
15:9 position ： Keep unused ;
8 position ： Read write control bit , As a slave device, you cannot control the direction , It can only be used as the main equipment ,’0’ Said to write ,’1’ Express reading ;
7:0 position ： Storage I2C Data sent or received on the bus , If you are operating the register and want to read, this bit is ignored , If you read this register, this bit stores the received data .

2.2.4 I2C eliminate TX_ABRT interrupt


chart 6
15:1 position ： Keep unused ;
0 position ： Clear the sending abnormal stop bit , Read this bit to clear the transmission abnormal stop interrupt , And send exception stop source register bit . Send... At the same time FIFO Refresh from / Released in the reset state , More writes can be allowed .

2.2.5 I2C Enable register


chart 7
15:1 position ： Keep unused ;
0 position ： Controller enable bit ;

2.2.6 I2C Status register


chart 8
15:7 position ： Keep unused ;
6 position ： Judge whether the slave device is active ;
5 position ： Determine whether the main equipment is active ;
4 position ： Judging reception FIFO Whether it is full ;
3 position ： Judging reception FIFO Is it empty ;
2 position ： Judge the transmission FIFO Whether it is full ;
1 position ： Judge the transmission FIFO Is it empty ;
0 position ： Judge I2C Whether the module is active .

2.2.7 I2C receive FIFO Number register


chart 9
15:6 position ： Keep unused ;
5:0 position ： receive FIFO How many bytes can be received .

2.2.8 I2C Send abnormal termination source register


chart 10
15 position ： When the master device needs to send data , But enter the state of reading data ;
14 position ： When sending data , The slave device loses the bus ;
13 position ： When the slave device wants to receive data ,FIFO There are already some data in ;
12 position ： Loss of arbitration ;
11 position ： When the main equipment is unavailable , The user operates the main equipment ;
10 position ： Restart unavailable , And the main equipment is 10 Send read command in bit address mode ;
9 position ： Restart unavailable , But the user sends a start byte ;
8 position ： Restart unavailable , But the user tried to send data in high-speed mode ;
7 position ： The master device has sent a start byte , And the start byte is confirmed ;
6 position ： The main device is in high-speed mode , And confirmed ;
5 position ： Read after the master device controller broadcasts ;
4 position ： The master device sends a broadcast , But it was not confirmed from the device ;
3 position ： Only the main equipment is valid , The master device has sent the address , And confirm , But no confirmation signal can be obtained when sending data ;
2 position ： Use of main equipment 10 Bit address mode ,10 The second byte of the bit address is not acknowledged by any slave device ;
1 position ： Use of main equipment 10 Bit address mode ,10 The first byte of the bit address is not acknowledged by any slave device ;
0 position ： Use of main equipment 7 Bit address mode , But it was not confirmed by any slave device .

2.3 Explanation of register configuration

#define CLK_PER_REG (* ( volatile uint16*)0x50000004)
#define I2C_CON_REG (* ( volatile uint16*)0x50001300)
#define I2C_TAR_REG (* ( volatile uint16*)0x50001304)
#define I2C_DATA_CMD_REG (* ( volatile uint16*)0x50001310)
#define I2C_CLR_TX_ABRT_REG (* ( volatile uint16*)0x50001354)
#define I2C_ENABLE_REG (* ( volatile uint16*)0x5000136C)
#define I2C_STATUS_REG (* ( volatile uint16*)0x50001370)
#define I2C_RXFLR_REG (* ( volatile uint16*)0x50001378)
#define I2C_TX_ABRT_SOURCE_REG (* ( volatile uint16*)0x50001380)
start-up I2C Module clock ：CLK_PER_REG |= 0x0020;
I2C Initialization register configuration of ：
Shut down first I2C controller , I2C_ENABLE_REG=0x00;
Set to main mode , Turn off slave mode , You can start again , The speed is set to fast , The address is 7 Bit mode (0x0000000001100101), I2C_ CON _REG =0x0065;
Set the target device address to 0x51, I2C_TAR_REG =0x51;
open I2C controller , I2C_ENABLE_REG=0x01;
Wait for the controller to be ready ,while( (I2C_STATUS_REG & 0x20) != 0 );
The read address is 0x98 One byte at , Send the address first I2C_DATA_CMD_REG = 0x98; Wait for the transmission to finish while((I2C_STATUS_REG&0x0002)==0); Send read instructions I2C_DATA_CMD_REG = 0x0100; Wait for the transmission to finish while((I2C_STATUS_REG&0x0004)==0); Then wait for the data to be received while(I2C_RXFLR_REG == 0); Reading the data in the receive buffer is the receive data rx_data = I2C_DATA_CMD_REG;
To the address of 0x98 Write a byte at 0xaa, Send the address first I2C_DATA_CMD_REG = 0x98; Wait for the transmission to finish while((I2C_STATUS_REG&0x0002)==0); send data I2C_DATA_CMD_REG = 0xaa; Wait for the transmission to finish while((I2C_STATUS_REG&0x0004)==0);




In the third quarter I2C experiment

The modules used in the experiment are ： Bottom plate of mobile phone development board ,Jlink Debugging tools , DuPont line 、 Heart rate and body temperature module 、3.7V Lithium battery or Mocro USB Line .
Connect the heart rate and body temperature module to the main control base plate through DuPont line , The connection is as follows ：
(1) One end of the heart rate and body temperature module needs to use DuPont cable to connect the heart rate and body temperature module 3V3、GND、SCL、SDA Four pins , As shown in the figure below ：


chart 11
(2) One end of the main control board of the mobile phone needs to be connected with DuPont cable J4 Of 2 Pins and J10 The two pins of the heart rate and body temperature module correspond one by one , As shown in the figure below

chart 12
Use JLINK Connect the mobile phone through DuPont line. Bluetooth is located on the main control backplane of the mobile phone , 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 ：


chart 13
(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 ：


chart 14
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 I2C Experimental Keil engineering i2c_eeprom.uvproj, Located in the directory ：
..\WT_Mobile\1. Junior course \DA14580\5_ primary _I2C\projects\target_apps\peripheral_examples\i2c\i2c_eeprom\Keil_5, As shown in the figure below ：


chart 15
stay KEIL Compile source code , Click on DEBUG, Then click Run at full speed , Place a breakpoint under the variable that stores the temperature data , When the program reaches the breakpoint, it will stop . Add this variable to the variable view window , You can see the temperature value , As shown in the figure below ：