Comments on my project

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1

Hi Guys,

I am a radio ham and I want to see if the Arduino Diecimila is suitable for my new project.

I want to make a tuning control for a radio. I am going to use a rotary encoder for the "knob" (3 digital pins), a 2 x 20 line Hitachi LCD display to display the frequency (6 digital pins), a 4x4 keypad (8 pins) for direct frequency entry and an Si570 oscillator chip to generate the frequency (I2C 2 pins). Getting the Si570 on the right frequency requires the calculation of a 32 bit number which is then passed to the Si570 via the I2C interface.

I also want to be able to control the Si570 from software running on the PC via the USB port on the Arduino. So I need to use one pin to tell the arduino if it, or the PC has control.

My initial thoughts are that I have insufficient digital IO pins, the Diecimilia has 14 and I need 18. One way around this might be to use an analog pin to interface with the keypad via an array of resistors configured so that when a button is pressed a unique resistance is presented to the pin. Or I could use a serial LCD but these are expensive, or an I2C lcd but i am not sure if these can share the same bus as the Si570.

Er, thats it...other than I have some "old school" programming skills...and this is my first Arduino project....

Comments, advice gratefully received...

2

All of the analog inputs can also be used for digital inputs. Problem solved.

3

It's probably also worth noting that rotary encoders only require two pins - the other one is either a ground or power pin. Also, if you want to be able to use the USART to communicate to the PC, pins 0 and 1 are already taken up. Thus, if you want to reduce pin count, it would be a good idea to use a shift register (you could drop your LCD to use only three pins, and probably use two shift registers with the keypad, making that lower as well).

4

Take a look at this arduino shield I made to teach myself Morse code. It has an LCD, 6 buttons, buzzer and you can put RJ45 connectors on to connect to other stuff. You could use an up and a down button to change frequency using my library. You don't have to use my hardware if you have similar hardware already.

5

Guys,

Thanks for all your help...I'll post my results here...

Steve