Example description
The I2C example shows how to use I2C interface in master and slave mode using POLLING/INTERRUPT method.
To use the example, connect a serial cable to the board's RS232/UART port and start a terminal program to monitor the port. The terminal program on the host PC should be setup for 115K8N1.
For boards that does not have default UART, the user can enable debugging, by defining ENABLE_DEBUG macro in sys_config.h and then connect FTDI UART cable to the board to use the full functionality of the example. If no UART can be connected see the paragraph below for using the example without uart
If there is no UART connected to Xpresso board, and if ENABLE_DEBUG is not defined then make connections as specified in the "Special connection requirements" section. When the board is reset or powered ON, the Master I2C will write to the IO Expansion slave making the RED LED Glow, and the example will terminate
After a Main menu is displayed via UART, I2C0 and I2C1 are configured with 100KHz speed.
User can access any I2C slave device (probe all devices by selecting option 3 from main menu) connected to the bus using this example, i.e, operations like WRITE/READ/WRITE&READ can be carried out by using any I2C I2C0/I2C1 as master. The input from UART could be decimal, hexadecimal (prefixed with 0x), or octal (prefixed with 0) and can be edited using backspace. User must press enter key to complete the input.
This example simulates two slave devices (default by I2C0), an EEPROM (0x5A) and an IO Extension device (0x5B). The EEPROM simulation is just to show how the I2C can be used as a device (it will not retain contents across power cycles). IO extention device have 2 ports, any single byte read will read 8 bit data from IN port (8 bit input reg0), any single byte write will write to OUT port (8 bit output reg1). Multibyte reads will read (IN REG, OUT REG) repeatedly, multi byte writes will write to OUT REG repeatedly. OUT REG represent LEDS in the board set/reset them will turn LED0-LED7 (If present) to ON/OFF, IN REG represent key press (KEY0 to KEY7).
To turn on LED1 and LED2, follow the steps given below
- Select I2C1 as default device by selecting option 1 and 1
- Select option 5 to write data to slave
- Enter 0x5B as the slave device address
- Enter 1 as the number of bytes to write
- Enter 6 as the data [Turn ON LED1 and LED2]
The EEPROM slave (simulation) device will work as any standard I2C EEPROM. To write data 0xDE, 0xAD, 0xBE, 0xEF to address 0x10, 0x11, 0x12 & 0x13 respectively and to read back the full content of the EEPROM follow the steps
- Select I2C1 as default device by choosing option 1 and give input 1
- Select option 5 to write data to slave
- Enter 0x5A as the slave device address
- Enter 5 as the number of bytes to write
- Enter 0x10 as the address to write
First byte written to device is always considered as the address from/to which read/write to be performed, the EEPROM uses 64 byte memory hence BIT0 to BIT5 will have address A0-A5 and BIT6 & BIT7 are don't cares. For every read/write the address will auto increment upon reaching the end of the device the address will automatically roll back to location 0.
- Enter data 0xDE,0xAD,0xBE,0xEF one by one
- Select option 6 to write/read the data from EEPROM
- Enter 0x5A as the slave address
- Enter 64 as the number of bytes to read
- Enter 1 as the number of bytes to write
- Enter 0 as the address from which read must start
- Full content of EEPROM will be displayed on UART terminal with address 0x10 to 0x13 showing the data written in previous operation.
Special connection requirements
- EA-DEVKIT 1788/4088
- I2C1_SDA (J5 pin 45) connected to I2C0_SDA (J5 pin 25)
- I2C1_SCL (J5 pin 54) connected to I2C0_SCL (J5 pin 26)
- Jumper J5 is the 64 pin expansion connecter close to 200pin OEM board connector
- Make sure double check the connected pins as there is a great possibility of connecting wrong pins
- LPCXpresso 1769 (using UART3)
- P0.19(SDA1) PAD17 connected to P0.27(SDA0) J6-PIN25
- P0.20(SCL1) PAD18 connected to P0.28(SCL0) J6-PIN26
Build procedures:
LPC17xx/40xx example quickstart for Keil uVision4
LPC17xx/40xx example quickstart for IAR EWARM
LPC17xx/40xx example quickstart for Code Red Xpresso
Supported boards and board setup:
Embedded Artists' LPC1788 Developer's Kit
Embedded Artists' LPC4088 Developer's Kit
NXP Xpresso LPC1769 board
Submitting LPCOpen issues:
Community support for LPCOpen
| #define I2C_SLAVE_EEPROM_ADDR 0x5A |
| #define I2C_SLAVE_EEPROM_SIZE 64 |
| #define I2C_SLAVE_IOX_ADDR 0x5B |
| #define SPEED_100KHZ 100000 |
| #define SPEED_400KHZ 400000 |
| static int con_get_input |
( |
const char * |
str | ) |
|
|
static |
| static void con_print_data |
( |
const uint8_t * |
dat, |
|
|
int |
sz |
|
) |
| |
|
static |
| void I2C0_IRQHandler |
( |
void |
| ) |
|
I2C0 Interrupt handler.
- Returns
- None
Definition at line 474 of file i2c.c.
| void I2C1_IRQHandler |
( |
void |
| ) |
|
I2C Interrupt Handler.
- Returns
- None
Definition at line 465 of file i2c.c.
| static void i2c_app_init |
( |
I2C_ID_T |
id, |
|
|
int |
speed |
|
) |
| |
|
static |
| static void i2c_eeprom_init |
( |
I2C_ID_T |
id | ) |
|
|
static |
| static void i2c_eeprom_update_state |
( |
I2C_XFER_T * |
xfer, |
|
|
uint8_t * |
buff, |
|
|
int |
sz |
|
) |
| |
|
static |
| void i2c_iox_update_regs |
( |
int |
ops | ) |
|
| static int i2c_menu |
( |
void |
| ) |
|
|
static |
| static void i2c_probe_slaves |
( |
I2C_ID_T |
i2c | ) |
|
|
static |
| static void i2c_rw_input |
( |
I2C_XFER_T * |
xfer, |
|
|
int |
ops |
|
) |
| |
|
static |
| static void i2c_set_mode |
( |
I2C_ID_T |
id, |
|
|
int |
polling |
|
) |
| |
|
static |
| static void i2c_state_handling |
( |
I2C_ID_T |
id | ) |
|
|
static |
Main program body.
- Returns
- int
Definition at line 483 of file i2c.c.
| void SysTick_Handler |
( |
void |
| ) |
|
SysTick Interrupt Handler.
SysTick 1mS tick handler.
- Returns
- Nothing
- Note
- Systick interrupt handler updates the button status
Definition at line 456 of file i2c.c.
1.8.2 
