ANY-maze Help > I/O devices supported by ANY-maze > Legacy I/O devices > The ANY-maze interface (AMi) > The AMi ports > The AMi General Purpose I/O ports
The AMi General Purpose I/O ports
Introduction
As the name implies, the General Purpose I/O (GPIO) ports can be used to connect a range of different devices to AMi. These include simple on/off switches, photobeams, touch switches, rotary encoders, etc.
As these ports are so versatile, AMi includes 16 of them (8 on the front and 8 on the back) each using a screw terminal block which can be unplugged from AMi to make connecting a device very easy.
| • | Devices that can connect to a GPIO port |
| • | Configuring the GPIO ports |
| • | General specification of a GPIO port |
Devices that can connect to a GPIO port
A GPIO port can be used to connect to the following devices:
| • | Simple on/off input switches |
| • | TTL level inputs |
| • | Photobeams |
| • | AMi photobeam arrays |
| • | AMi touch switches |
| • | Rotary encoders |
| • | TTL level outputs |
| • | Solid state relay output |
Configuring the GPIO ports
Because you can connect different types of devices to a GPIO port, AMi needs to know what has actually been connected so it can use it. This is done using the General Purpose I/O page of the AMi configuration window - see figure 1 below.
Figure 1. The General Purpose I/O page of the AMi configuration window.
To learn more, refer to the General Purpose I/O tab topic.
General specification of a GPIO port
A GPIO port has four 'pins'; these are (from left to right):
| Pin 1 | Control line |
| Pin 2 | 5 volts |
| Pin 3 | Data line |
| Pin 4 | Ground (0 volts) |
Control line
The control line is used to switch photobeams on and off and to multiplex the inputs of rotary encoders. It is unlikely that you will find this line useful in your own circuits.
The 5 Volts line
The 5 volts line provides power at 5 volts. This line is connected to the AMi current limited power supply, which means that you can't draw much current from it. The exact limit is not defined for each port, but rather for all the devices that use the current limited power supply. Specifically, when AMi is powered from the USB bus, the limit is 65mA; when AMi is powered from the DC power supply, the limit is 300mA. So, the total you can draw from this supply per port will depend on how many ports you are using and how AMi is being powered.
Note also that this supply is short circuit protected. Any short will cause the supply to be shut down and the ANY-maze software will display a message. When the short circuit is repaired, the supply will switch back on automatically.
Data line
The data line is programmed either as an input or as an output, depending on the port's configuration. To make the port into a general purpose TTL level input, program the port as a 'switch input'; to make it into a general purpose TTL level output, program it as a 'switch output'.
If you wish, you can connect your own circuitry to this line and power it from pin 2. Note that this line is pulled up to 5V (pin 2) through a 15K resistor.
Ground line
This line is connected to AMi GND. Note that the AMi is entirely isolated (1000V isolation) from the host PC (both USB power and USB data are isolated). Thus, AMi GND and PC GND will not necessarily be at the same level and should not be connected together.
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ANY-maze help topic T1161