User Manual
PD-1021 Hardware Manual (Rev. 1.00 / 2012-JUN-20) 13
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3.6 Inputs and Outputs
3.6.1 Digital Inputs IN_0, IN_1, IN_2, IN_3
The eight pin connector of the PD-1021 provides four general purpose inputs IN_0, IN_1, IN_2 and IN_3.
The first two inputs have dedicated connector pins while the other two share pins with two general
purpose outputs.
All four inputs are protected using voltage resistor dividers together with limiting diodes against
voltages below 0V (GND) and above +3.3V DC (see figure below).
+3.3V
IN_0
IN_1
IN_2
IN_3
microcontroller
and TMC262
10k
10k
1nF
GND
GND GND
Figure 3.7: General purpose inputs
The four inputs have alternate functionality depending on configuration in software. The following
functions are available:
Label
(connector pin)
Default Function
Alternate function 1
Alternate function 2
IN_0 (5)
Digital input
Step signal input
(connected to TMC262 step input)
Left stop switch
IN_1 (6)
Digital input
Direction signal input
(connected to TMC262 direction input)
Right stop switch
OUT_0 / IN_2 (7)
Output
Digital input
Home switch
OUT_1 / IN_3 (8)
Output
Digital input
Analog input
(0… +6.6V, 12bit resolution)
Table 3.5: Multi-purpose inputs / alternate functions
All four inputs are connected to the on-board processor and can be used as general purpose digital
inputs.
Using the alternate functionality of IN_0 and IN_1 it is possible to control the on-board stepper motor
driver with the help of an external stepper motor controller using step and direction signals. For the step
and direction signals the signal levels are the same as for the general purpose digital inputs.
IN_3 can be used as analog input, also. A 12bit analog to digital converter integrated in the
microcontroller will convert any analog input voltage between 0 and +6.6V to a digital value between 0
and 4095 then.