Peek

Syntax:

    OutputVariable = Peek (location)

Command Availability:

Available on all microcontrollers.

Explanation:

The Peek function reads information from the on-chip RAM of the microcontroller.

location is a word variable that gives the address to read. The exact range of valid values varies from chip to chip.

This command should not normally be used, since it makes porting code to another chip very difficult — register and RAM addresses are chip-specific.

Example #1:

    'This program will read and check a value from PORTA
    'This specific peek will only work on some microcontrollers
    Temp = Peek(5)          ' <<< the Peek instruction
    IF Temp.2 ON THEN SET green ON
    IF Temp.2 OFF THEN SET red ON

Key line: Temp = Peek(5) — reads the raw byte value at RAM/register address 5 directly, bypassing the named-port abstraction GCBASIC normally provides, which is why the result is chip-specific.

Example #2:

    ' This subroutine will toggle the pin state.
    ' You must change the parameters for your specific chip.
    ' Usage as show in examples below.
    '
    '      Toggle @PORTE, 2 ' equates to RE1.
    '      Wait 100  ms
    '      Toggle @PORTE, 2
    '      Wait 100 ms


    ' Port , Pin address in Binary
    ' Pin0 = 1
    ' Pin1 = 2
    ' Pin2 = 4
    ' Pin3 = 8
    '
    ' You can toggle any number of pins.
    ' Toggle @PORTE, 0x55
    Sub Toggle ( In DestPort As word, In DestBit )
          Poke DestPort, Peek(DestPort) xor DestBit          ' <<< the Peek instruction, paired with Poke
    End sub

Key line: Poke DestPort, Peek(DestPort) xor DestBit — reads the port’s current value with Peek, flips the requested bit(s) with xor, and writes the result straight back with Poke, toggling those pins without disturbing the others.

See Also:

  • Poke — writing back to the location this page reads
Prev  Up  Next
  Home