OLIMEX MOD-IO User Manual page 14

IN1, IN2 IN3, IN4
Please note that the opto-isolated inputs IN1, IN2, IN3, IN4 in earlier revisions were able to receive
signals in the 3V to 6V range. R27, R29, R31, R33 were 330R and R28, R30, R32, R34 were R4.7k.
We have now adjusted the values of the resistors in that part of the schematic in latest revisions to
allow higher voltage input in the 3.3V-24.0V range. R27, R29, R31, R33 are now R3.9k and R28, R30,
R32, R34 are now R47k
OUT1, OUT2, OUT3, OUT4
AIN-1
Please note that the analog inputs by default are as big as the input levels but you might change this.
Just calculate the needed resistors R19/R20 and R21/R22.
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Pin #
1
2
IN1 connected to (T0)PB0 – signal I4
IN2 connected to (T1)PB1 – signal I3
IN2 connected to (AIN0/INT2)PB2 – signal I2
IN4 connected to (INT1)PD3 – signal I1
OUT1 connected to (ADC3)PA3 – signal name O4
OUT2 connected to (ADC2)PA2 – signal name O3
OUT3 connected to (ADC1)PA1 – signal name O2
OUT4 connected to (ADC0)PA0 – signal name O1
Pin # Signal Name Connected to
1 3.3V
2 AN1
3 AN2
Signal
-
+
VCC
(ADC7)PA7
(ADC6)PA6
Page 14