HB 08M 1 - The starting story

The PICAXE 08M microcontroller bristles with features such as infrared receive and transmission, tune commands and basic input and output via switches and lights. Following the successful PICAXE training course in August 2005 with 21 teachers it was felt that a very useful teaching module should allow students to explore a range of these options - the HB08M 1 was born and designed by teachers and students..

The HB 1 board can be made by students with the supplied PCB Design and Make files supplied by Intellecta Technologies. Some schools wanted to have kits that can be soldered by students and the Revision boards were produced. These features silk screened annotations that make it easy to assemble the boards. The solder mask makes it easy to solder. These can be purchased directly from Intellecta as bare boards or complete kits.

This system uses a number of links to select options such as:

>>>Allow 2 switches to be read

This means students can set up the switches to perform tasks such as:

1. Turn ON on led 1 when switch 1 is pressed, Turn ON led 2 when switch 2 is pressed.

2. Use one switch to increase the pitch of the buzzer and the other switch can decrease the pitch

3. Study two input AND, NAND, OR, and logic operations

4. Send out 3 different infrared values depending on the switch combination

5. Use the switches to set up an up-down counter

6. Use the switches to set up a set/reset flip flop

7. Turn ON the buzzer with one switch and Turn it off with the other switch

>>>Set up the infra red receiver

8. Show the value of the received commands on the three leds ( digital representation)

9. Send out the command on the infrared transmission led

>>>Set up the light sensor

10. Show the value of the three leds

11. Link the pitch command to the light value

12. Transmit the light value via the infra-red led

>>Use Infrared LED

The infra-red transmission led is very useful to send our special coded information that can be read by other devices.

13. Send out switch status via the infrared led commands

14. Send out the light sensor value.

Discussion of circuit

The various options on the circuit board are selected with jumpers that fit over posts on the board. This modular selection means it is easier to discuss the operation in this manner.

Main connector

This is a male 10 way 90 degree header that connects to the 08M. The pins are labelled as PIN1,2,3, etc to match exactly the names of the pins on the 08M. This means that the pin labelled PIN3 can be configured to be IN4, OUT4 or ADC4.

Note that the pins are labelled with numbers at the ends of the connector so you can get the correct orientation

Functions of the lines

The 08M has many functions and these are shown in the next figure. The actual BASIC code must take into acount the selection of the function with these jumpers.

J1 Selection of visible led D2 or infrared led D1

The jumper J1 selects either the red led labelled D2 or the infra red led D1. This is normally a dark or black led.

The selector is connected to PIN7 so the red led D2 is controlled with an OUT0 command or LET PINS command

Example:
let pins = %11000011 ‘ switch outputs 7,6,0,1 on
pause 1000 ‘ wait 1 second
let pins = %00000000 ‘ switch all outputs off

. The INFRAOUT command is automatically linked to PIN7

J2 Selection of buzzer of led D4

The jumper J2 selects either the red led labelled D4 or the buzzer B1

The selector is connected to PIN5 so the red led D4 is turned on with an OUT2 command.

The TUNE command is automatically linked to PIN5.

The SOUND command is

SOUND  2,(100,20)

J3 Selection of IR receiver or Switch S2

The jumper J3 selects either the infrared receiver or the switch S2.

The selector is connected to PIN4 so the switch S2 is controlled with the IN3 command

J4 Selection of visible light sensor or Switch S1

The jumper J3 selects either the switch input S1 or the light dependent resistor. The commands are read with the IN4 or readadc , 4, variable command.