AVR-ICSP View Datasheet(PDF) - Unspecified

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Description

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AVR-ICSP

Open-source hardware UEXT extension board with relays and USER’S MANUAL

Unspecified 

OLIMEX© 2015

MOD-IO user's manual

2.6.2 Getting the state of optocoupler

The board features four optoisolated inputs named IN1, IN2, IN3 and IN4 and their statuses can be

read together with one command. The command should have the following format:

************************************

S aaaaaaaW cccccccc P S aaaaaaaR 0000dddd P

************************************

,where

S – start condition

aaaaaaa – slave address of the board

W – write mode, should be 0

cccccccc – command code, should be 0×20

P – Stop condition

R – read mode, should be 1

dddd – bitmap of the input states received from the MOD-IO board, i.e. bit0 corresponds to

IN1, bit1 to IN2 and so on. '1' means that power is applied to the optocoupler, '0' means the

opposite.

Note: Successive readings from the board without reissuing the command code will not get an

updated value of the ports (i.e. the user will read the same value) until another command is issued.

Example:

Reading optocoupled inputs in pseudo code

i2cStart()

i2cSend(0xb0);

i2csend(0x20);

i2cClose();

i2cStart();

i2cSend(0xb1);

byte = i2cRead();

i2cClose();

//Send start condition;

//This is 0×58 shifted to left one time and added 0 as W

//Read inputs commands

//Send stop condition

//Send start condition. You can use i2cRestart() instead

//This is 0×58 shifted to left one time and added 1 as W

//Read one byte of data;

/* “byte” now holds the state of the inputs. To “decode” bitmask the data. */

in1 = byte & 0x01; //To get state of IN1

in2 = byte & 0x02; //To get state of IN2

in3 = byte & 0x04; //To get state of IN3

in4 = byte & 0x08; //To get state of IN4

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