ANY-maze Help > I/O devices supported by ANY-maze > Accessories designed specifically for ANY-maze > The ANY-maze TTL cable > Using the ANY-maze TTL cable outputs

Using the ANY-maze TTL cable outputs

Introduction

TTL is a standard for digital signals, and many devices that accept digital inputs use TTL logic levels. For example, some shockers include TTL inputs which can be used to control when the shock is on and off; and some pellet dispensers will dispense a pellet in response to a TTL 'pulse' on their input.

The ANY-maze cable TTL output

The ANY-maze TTL cable provides two ports, both of which can be individually configured as TTL outputs. The outputs are referenced to GND, which is the centre terminal.

By default the TTL outputs are active low; that is to say that normally they will be high (i.e. a logical 1) and will go low (to a logical 0) when activated. You can change the active state of the inputs to be Active high using options on the TTL cable configuration window.

ANY-maze cable TTL output specification

Active state

Configurable. Default = Low

High level voltage

Typical 4.1V, Min 3.2V

Low level voltage

Typical 0.4V, Max 0.6V

Maximum current

6mA (source/sink)

Max switching frequency

50Hz

Connecting an output to something

To control a device that has a TTL level input, you simply need to connect the output and GND lines from the cable to the device's input and GND lines. However, a little caution is advisable. The cable's TTL output can only source or sink 6mA, which is quite a low current. If you are trying to connect a device that has an optically isolated input (which may even claim to be a TTL input), then you should first check the current that the input will draw.

If you want to control something that doesn't have a TTL level input, for example you want to switch a lamp on and off, then you will need to use some additional circuit which will be controlled by the TTL output. This might not be as complicated as it sounds; for example a Google search for 'TTL Relay Board' will probably turn up a number of suitable and inexpensive devices.

Using an output within an experiment

In order to use an output in an experiment, it must be included in the protocol. This is a simple process and is described in detail the Setting up an on/off output topic.