User manual

TMCM-1021 V1.2 Hardware Manual (Ref. 1.00 / 2012-MAR-09) 11
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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.
3.5.2 General Purpose Outputs
The eight pin connector of the TMCM-1021 provides two general purpose outputs. These two outputs are
open-drain outputs and can sink up to 100mA each. The outputs of the N-channel MOSFET transistors are
connected to freewheeling diodes each for protection against voltage spikes especially from inductive loads
(relais etc.).
Both outputs OUT_0 and OUT_1 share pins with two of the four inputs (IN_2 resp. IN_3).
Please take into account the 20k (2x 10k in series) resistance to ground (transistor not active) of the input
voltage divider (figure 4.8) when designing the external “load” circuit.
VDD
OUT_0 / IN_2
OUT_1 / IN_3
microcontroller
GND
+3.3V
microcontroller
10k
10k
1nF
GND
GND GND
Figure 3.8: General purpose outputs