HSerGetString

Syntax:

    HSerGetString myString      ‘Get a multi char string  from USART 1
    HSerGetString myString,1    ‘Get a multi char string  from USART 1
    HSerGetString myString,2    ‘Get a multi char string  from USART 2
Variable type is string and the  routine checks for numbers,letters, and puctuation.

Command Availability:

Available on all microcontrollers with a USART or UART module.

Microchip PIC supports USART1 and 2.
Atmel AVR supports USART 1,2,3 and 4.

Enabling Constants:

To enable the use of the USART these are the enabling constants.   These constants are required.  You can change the USART_BAUD_RATE and to meet your needs.  For addition USART ports use #define USARTn_BAUD_RATE 9600 where n` is the required port number. 

    'USART settings for USART1
    #define USART_BAUD_RATE 9600
    #define USART_TX_BLOCKING
    #define USART_DELAY OFF

Explanation:

This command will read a multi character string received as ascii input to the hardware serial module followed by a CR from an external serial source. It can be used only as a subroutine. Variable type is string and the routine checks for numbers,letters, and puctuation.

Example:

  'This program receives char string and CR from a PC terminal, sends back the string on the serial port, and turns Led’s on off by command

  #chip 18f26k22, 16

  'Set the pin directions
  #define USART_BAUD_RATE 9600
  #define USART_BLOCKING
  #define USART2_BAUD_RATE 9600
  #define USART2_BLOCKING

  'InitUSART
  #define SerInPort PORTc.7    'USART 1 Rx Pin
  #define SerOutPort PORTc.6    'USART 1 Tx Pin


  'Set pin directions
  Dir SerOutPort Out
  Dir SerInPort In

  Dir PORTB.6 Out        'second USART Tx Pin
  Dir PORTB.7 In        'second USART Rx Pin

  Dir PORTB.0 Out        ' LED hooked up for testing
  Dir PORTB.1 Out        ' LED hooked up for testing

  Wait 100 Ms

  ; ----- Variables
  ' All byte variables are defined upon use.
  Dim myNum as Word
  Dim MyString as String

  ; ----- Main body of program commences here.
  'Message after reset
  HSerPrint "18F26k22"
  HSerPrintCRLF

  'Main routine

  Do Forever

    HSerGetString MyString          ' <<< the HSerGetString instruction
    HSerPrint MyString
    HSerSend(13)
     If MyString = "LED1 ON" Then
       Set PORTB.0 Off
     End If
     If MyString = "LED1 OFF" Then
       Set PORTB.0 On
     End If
     If MyString = "LED2 ON" Then
       Set PORTB.1 Off
     End If
     If MyString = "LED2 OFF" Then
       Set PORTB.1 On
     End If

  Loop

Key line: HSerGetString MyString — blocks while reading letters, digits, and punctuation from the default USART, until it sees the terminating carriage return, then stores the assembled text in MyString, which the program then compares against expected commands such as "LED1 ON".

See Also:

  • HSerReceive — reading a single raw byte instead of a whole string
  • HSerGetNum — reading a whole number instead of a text string
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