Mikroelektronika MIKROE-724 データシート

mikroBasic PRO for dsPIC30/33 and PIC24

MikroElektronika

445

Library Example

The example demonstrates working with the dsPIC as a Master node in RS-485 communication. Master sends message

to Slave with address 160 and waits for a response. After the response is received, the first byte of received data is

incremented and sent back to the Slave. The received data is displayed on PORTB while error on receiving (0xAA)

and number of consecutive unsuccessful retries are displayed on PORTD. Hardware configurations in this example are

made for the EasydsPIC4A board and dsPIC30F4013.

RS485 Master code:

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program RS485_Master_Example

dim dat as byte[10] ‘ buffer for receving/sending messages

i, j as byte

cnt as longint

dim rs485_rxtx_pin as sbit at RF2_bit ‘ set transcieve pin

rs485_rxtx_pin_direction as sbit at TRISF2_bit ‘ set transcieve pin direction

‘ Interrupt routine

sub procedure interrupt() org IVT_ADDR_U2RXINTERRUPT

RS485Master_Receive(dat)

U2RXIF_bit = 0 ‘ ensure interrupt not pending

end sub

main:

cnt = 0

ADPCFG = 0xFFFF

PORTB = 0

PORTD = 0

TRISB = 0

TRISD = 0

UART2_Init(9600) ‘ initialize UART2 module

Delay_ms(100)

RS485Master_Init() ‘ initialize MCU as Master

dat[0] = 0xAA

dat[1] = 0xF0

dat[2] = 0x0F

dat[4] = 0 ‘ ensure that message received flag is 0

dat[5] = 0 ‘ ensure that error flag is 0

dat[6] = 0

RS485Master_Send(dat,1,160)

URXISEL1_U2STA_bit = 0

NSTDIS_bit = 1 ‘ no nesting of interrupts

U2RXIF_bit = 0 ‘ ensure interrupt not pending