User manual

TMCM-6110 Hardware Manual (V1.10 / 2012-JAN-25) 14

6. BUS TERMINATION:

Especially for longer busses and/or multiple nodes connected to the bus and/or high communication

speeds, the bus should be properly terminated at both ends. The TMCM-6110 does not integrate any

termination resistor. Therefore, 120 Ohm termination resistors at both ends of the bus have to be

added externally.

7. NUMBER OF NODES:

The bus transceiver used on the TMCM-6110 units (TJA1050T) supports at least 110 nodes under

optimum conditions. Practically achievable number of nodes per CAN bus highly depends on bus length

(longer bus -> less nodes) and communication speed (higher speed -> less nodes).

4.5.3 USB

For remote control and communication with a host system the TMCM-6110 provides a USB 2.0 full-speed

(12Mbit/s) interface (mini-USB connector). As soon as a USB-Host is connected the module will accept

commands via USB. The CAN interface will be de-activated then.

The TMCM-6110 support USB self powered operation (when an external power is supplied via the power supply

connector) and USB bus powered operation, also (no external power supply via power supply connector).

During USB bus powered operation, only the core digital circuit parts will be operational. That is, the

microcontroller itself and also the EEPROM. Motor movements will not be possible. This mode has been

implemented in order to enable configuration / parameter setting / read-out, firmware updates etc. by just

connecting a USB cable between the module and a host PC. No additional cabling / external devices as e.g.

power supply etc. are required in that case.

Please note that the module might draw current from the USB +5V bus supply even in USB self powered

operation depending on the voltage level of this supply.

4.6 Inputs and Outputs

4.6.1 Reference switch inputs

The six reference switch connectors – one for each stepper motor axis – offer two reference switch inputs each,

REF_L and REF_R.

Both inputs offer the same input circuit with 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 separately

for the first three axes / first three reference switch connectors 0-2 and the second three axes / reference switch

connectors 3-5.

+3.3V

REF_L,

REF_R

TMC429

10k

22k

1nF

GND

GND GND

+5V

Figure 4.8: Reference switch input circuit (simplified diagram)