BS2 off of a BOE and powered by NiMh AA batteries

John Kauffman

I want to measure the temperature in a camping oven I take backpacking. I've done lots of projects with BS2 on a BOE but this is my first try to:
· - reduce size by building with a naked BS2 (wihtout the BOE)
· -·instead of the 9 volt, use NiMh AA batteries out of my GPS (recharged with a commercial solar charger)

The current draw, beyond the BS2 itself, is only for two thermistors in an RCTIME circuit and·several·LEDS for outputs that will report the temperature in a flashing code. The unit·will be turned on for·30 seconds to get a reading, about 60 readings in an evening.

Question #1 - Minimum voltage
If I'm just using a BS2 (no BOE) what is the minimum voltage I need?
Do I have to have to use four x 1.5 volt batteries or is there a way to get by with just 2 cells?
I'm always confused by the battey's + - system and the BS2 system of Vin, Vss an Vdd.·Battery red and black leads go to which pins on BS2?

Question #2 - BS2 without BOE
To run a naked BS2 (no BOE) what do I need besides the batteries?
Do I need a voltage regulator? If yes, which part number?
Do I need a·timing crystal?
Anything else?

Question #3 - Mounting BS2, sensors and LEDS
I'm assuming I can get a simple socket for the BS2 (like for an IC DIP) and then solder my battery leads, sensors and LEDS to the pins of the socket to end up with a very small package.
Sound OK?
Anyone have a source of the right size socket? I see it as part of Parallax part 27291, but I only need the socket.

Question #4 - Programming
I'm assuming I can program and test the BS2 in my BOE then remove it and place in the socket project mentioned above. Each time I put in the batteries it should auto-run until I remove the batteries. Sound right? Maybe I could splurge on weight for a switch [noparse]:)[/noparse]

Much thanks & when done I'll follow up with a post on the finished project for future reference.

allanlane5

The BS2 is very nice, because it has on-module a regulator (input from Vin, output to VDD, ground on VSS), an on-module resonator (no external oscillator needed). So you can connect 6 volts to 9 volts to the Vin pin, Ground to VSS, and the chip will run. Why not just use a single 9-volt?

It also has on-module EEPROM, so once programmed will re-run its program on power-up.

It can use a standard 24-pin 'wide DIP' socket. With liberal application of hot-glue once your circuit is soldered to a socket, you should be ok.

Answers:
1. I believe the minimum is 6 volts. Thus you need 4 AA cells. A 9-volt cell will work also.

2. All you need is a socket (so you can un-plug the BS2) and a power supply, wired from Vin to Vss. Everything else is on-module.

3. Yes, this should work. RadioShack sells a 24-pin wide DIP.

4. Yes, the BS2 program is safely stored for all time EEPROM. It re-runs on power-up.

Bean

If you are using NiCad or NiMh cells you will need 5 cells to get 6.0Volts.
Bean.

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