Documentation   :     F18 I/O    

 OUTPUT:

THE IO REGISTER: An 18-bit control and status register, named io and diagrammed below, is each F18A’s interface with its I/O circuitry (if any) and comm port handshake lines. In the “READ” line of the table below, the green background indicates signals that, if they exist, come from other nodes or the world outside

IO Register :    

IO Register :       Bits 17  16

10000   io r!     ( weak pull down )

30000   io r!     ( drive pin High )

0           io  r!    ( high impedance )

In ArrayForth :    Communication with GA144

host  load panel

with node 500  ( GPIO-500.17  pin 7 )

talk 0 500 hook upd

GPIO output  :

0, 10000, 30000   {Hexa}    io   r!   

!!  Press  F1   (decimal  -->  Hexadecimal)

     Example :      

10000   io r!     ( weak pull down )

30000   io r!     ( drive pin High )

0           io  r!    ( high impedance )

 INPUT:

IO Register :  Bit 17  read  pin 17

GPIO input  :       !!     Before write  0   ( High impedance )

   io   r@   

Exemple :                 Read  when  GPIO-500.17 = 0    , and   when  GPIO-500.17 = "1"

GPIO-500.17 = 0       19FF

GPIO-500.17 = '1'     219FF

The schematic :

the switch is to put 1.8v on the GPIO 500.17