User Manual

TMCM-1311 V1.2 Hardware Manual (Rev. 1.12 / 2013-JUL-05) 18
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3.5 Inputs and Outputs
3.5.1 Encoder Input
The dedicated encoder connector offers support for the connection of an incremental encoder with a/b
signals and optional n/index-channel. Encoders with +5V TTL, open-collector, or differential output signals
can be connected directly. A +5V output - available at one connector pin - can be used for the encoder
circuit supply. The on-board +5V switching voltage regulator has been designed in order to provide a
maximum of 100mA for external circuits (shared with external encoder and reference switch circuit).
A+
microcontroller
470R
+5V
A-
B+
470R 470R
B-
N+
N-
47
k
47
k
47
k
3k3
3k3
+5V
GND
120R 120R 120R
Termination
jumper
microcontroller
microcontroller
Figure 3.8 Encoder input circuit (simplified diagram)
3.5.2 Reference Switch Inputs
The reference switch connector provides two reference/limit switch inputs, REF_L and REF_R. Both inputs
offer the same input circuit including voltage resistor dividers, limiting diodes against over- and under-
voltage, and programmable 1k pull-ups to +5V. The programmable pull-ups can be switched on or off in
software (both together).
+3.3V
REF_L
REF_R
10k
22k
1nF
GND
GND GND
1k
+5V
microcontroller
Figure 3.9 Reference switch input circuit (simplified diagram)