Mikroelektronika MIKROE-724 データシート

440

mikoBasic PRO for dsPIC30/33 and PIC24

MikroElektronika

HW Connection

PWM Motor Control demonstration

RS-485 is a multipoint communication which allows multiple devices to be connected to a single bus. mikroBasic PRO 

for dsPIC30/33 and PIC24 provides a set of library routines for comfortable work with RS485 system using Master/

Slave  architecture.  Master  and  Slave  devices  interchange  packets  of  information.  Each  of  these  packets  contains 

synchronization  bytes,  CRC  byte,  address  byte  and  the  data.  Each  Slave  has  unique  address  and  receives  only 

packets addressed to it. The Slave can never initiate communication.

It is the user’s responsibility to ensure that only one device transmits via 485 bus at a time.

The RS-485 routines require the UART module. Pins of UART need to be attached to RS-485 interface transceiver, 

such as LTC485 or similar (see schematic at the bottom of this page).

- START byte value = 

150

 

- STOP byte value = 

169

 

- Address 

50

 is the broadcast address for all Slaves (packets containing address 

50

 will be received by all Slaves  

  except the Slaves with addresses 

150

 and 

169

). 

Important: 

- The library uses the UART module for communication. The user must initialize the appropriate UART module before  

  using the RS-485 Library. 

- For MCUs with multiple UART modules it is possible to initialize them and then switch by using the UART_Set_Active routine.  

if (current_duty > pwm_period) then       ‘ If we decrease current_duty greater then 

        current_duty = pwm_period         ‘ set current_duty to max possible value

      end if

      PWM1_MC_Set_Duty(current_duty,  1)        ‘ Set newly acquired duty ratio

    end if

    Delay_ms(5)                                 ‘ Slow down change pace a little

  wend