Circuit Notebook 93 - The TEP IQ2 Microcontroller Board

This is a small fully assembled PCB with a PIC 16F817 8-bit Microcontroller, pre-loaded with a control program. It is intended for pupil use in schools, but could have applications in amateur radio and ATV, in fact, almost anything. You don't need a programmer to program it. A picture of the Microcontroller, with terminal blocks added is shown in Fig.1. and the layout is shown in Fig.2.

The main features include:

Programming

Programming of the IQ2 is very easy. First of all, to create a line of program, set each of the outputs to either on or off. The LEDs adjacent to each of the press button switches indicate on or off status. (These enable both programming and test runs of program before anything is actually connected.) When the four outputs have been set, press the 'save' switch. All the output LEDs flash momentarily to confirm that this line of program has been saved. Re-set the outputs (or leave them alone) for the next line of program and press 'save' again. You can enter up to 248 lines of program in this way. However, you can only correct any errors by entering the whole program again.

To run the program, press the 'run' button and the green LED comes on. The output LEDs will light up in the sequence you programmed. The program loops continuously. The rate of stepping through the program may be controlled by the 'speed control'. The fastest rate is about 100 steps/second and the slowest about 20 seconds/step.

Sample program: single flashing light

Turn on outoput 1 - i.e. press the button so that LED 1 lights up

Press 'save'

Turn off output 1 - i.e. press the button again to turn off the LED

Press 'save'

Press 'run'

You have created a two line program that turns output 1 on and off. Because the program always loops back to the beginning, the flashing is continuous.

If you disconnect the battery and reconnect, the program will run again. It will only be deleted when you start entering a new program. Full information is provided in an 8 page information document provided with the IQ2 microcontroller.

Amateur radio and ATV applications

The first that comes to mind is a morse code 'ident' generator, for portable or repeater use, where the call sign is programmed in line by line. One of the outputs could key the TX or tone generator. For example, the lines of program for the letter 'A' (dit-dah) would be ON-off-ON-ON-ON-. My call sign would occupy 76 lines of program.

There are 2 inputs. The inputs enable you to start, stop and jump between different sections of a longer program and so allow you to select 4 separate sub-programs (Progs 0-3) which you have entered. Continuing from the above example, one program may have your call sign, another a 'K', another 'CQ' etc. and these could be selected by a switch as shown in Fig.3. and run independently.

In ATV, the IQ2 outputs could be used drive video/audio switches or multiplexers to switch sequentially, but in any order, up to 4 video sources and 4 audio sources or to switch a caption source on for a few seconds and the main signal on for an extended period. A suggested arrangement is shown in Fig.3. The input switch must be set to '0' when programming the IQ2.

The outputs are 'pull-down' open collector circuits, mainly suitable for relays etc but if used to drive other circuits then a 'pull-up' resistor of 10k ohms on each output will be required, as shown in Fig.3.

Acknowledgement

To Professor John Cave of Middlesex University for permission to reproduce the diagram and other information from the IQ2 document.

Figures and text

Fig.1. IQ2 Microcontroller with Terminal Blocks added

Fig.2. IQ2 Layout and connections

Fig.3. Suggested ATV use for the IQ2 Microcontroller

References

IQ2 Microcontroller Document Teaching Resources Ltd. Unit 10, The IO Centre, Lea Road, Waltham Cross, Herts EN9 1AS Tel. 01992 716052 www.mutr.co.uk

IQ2 Microcontroller (assembled) Teaching Resources Ltd IQ 002 Board £9.60 + £5.80 p&p + VAT (£18.10)