Pages: 1 [2]   Go Down
Author Topic: BASIC Computer Board Design  (Read 944 times)
0 Members and 1 Guest are viewing this topic.
Fort Lauderdale, FL
Offline Offline
Faraday Member
**
Karma: 71
Posts: 6144
Baldengineer
View Profile
WWW
 Bigger Bigger  Smaller Smaller  Reset Reset

If you're really serious about making a BASIC interpreter with stuff like motors, sensors, SD cards and such, maybe you should consider something other than the ATmega328.

Why not use the ATmega2560?  You'll start out with 8K of RAM (2X the original Apple I) and it supports extending the RAM with an external chip.   Maybe don't add the external RAM on the first board, but add it later on.

You'll have I/O for your on-board stuff with plenty left over for the user to do whatever they want.  The overall design isn't much more complicated than the ATmega328, though the PCB layout is a little bit more important given the chip's package.

Logged

Capacitor Expert By Day, Enginerd by night.  ||  Personal Blog: www.baldengineer.com  || Electronics Tutorials for Beginners:  www.addohms.c

Global Moderator
Boston area, metrowest
Offline Offline
Brattain Member
*****
Karma: 549
Posts: 27419
Author of "Arduino for Teens". Available for Design & Build services. Now with Unlimited Eagle board sizes!
View Profile
WWW
 Bigger Bigger  Smaller Smaller  Reset Reset

SD cards need couple hundred mA of 3.3V VCC and 3.3V level signals. 74HC4050 commonly used for  level conversion.
Logged

Designing & building electrical circuits for over 25 years. Check out the ATMega1284P based Bobuino and other '328P & '1284P creations & offerings at  www.crossroadsfencing.com/BobuinoRev17.
Arduino for Teens available at Amazon.com.

Offline Offline
Newbie
*
Karma: 0
Posts: 19
View Profile
 Bigger Bigger  Smaller Smaller  Reset Reset

Thanks for that, working on it now. My ultimate goal with this is to migrate from using the Arduino Bootloader to having no bootloader.
Logged

Offline Offline
Newbie
*
Karma: 0
Posts: 19
View Profile
 Bigger Bigger  Smaller Smaller  Reset Reset

If you're really serious about making a BASIC interpreter with stuff like motors, sensors, SD cards and such, maybe you should consider something other than the ATmega328.

Why not use the ATmega2560?  You'll start out with 8K of RAM (2X the original Apple I) and it supports extending the RAM with an external chip.   Maybe don't add the external RAM on the first board, but add it later on.

You'll have I/O for your on-board stuff with plenty left over for the user to do whatever they want.  The overall design isn't much more complicated than the ATmega328, though the PCB layout is a little bit more important given the chip's package.



The motor driver and servo stuff was more of a idea, not really serious. I would prefer to make the board work for the 1st revision, then add the ATMega2560 in a 2nd revision.

SD cards need couple hundred mA of 3.3V VCC and 3.3V level signals. 74HC4050 commonly used for  level conversion.

Thanks for that CrossRoads
Logged

Global Moderator
Boston area, metrowest
Offline Offline
Brattain Member
*****
Karma: 549
Posts: 27419
Author of "Arduino for Teens". Available for Design & Build services. Now with Unlimited Eagle board sizes!
View Profile
WWW
 Bigger Bigger  Smaller Smaller  Reset Reset

So why just load your sketch with an AVR ISP using File:Upload Using Programmer? Not far to migrate.
Logged

Designing & building electrical circuits for over 25 years. Check out the ATMega1284P based Bobuino and other '328P & '1284P creations & offerings at  www.crossroadsfencing.com/BobuinoRev17.
Arduino for Teens available at Amazon.com.

Offline Offline
Newbie
*
Karma: 0
Posts: 19
View Profile
 Bigger Bigger  Smaller Smaller  Reset Reset

So why just load your sketch with an AVR ISP using File:Upload Using Programmer? Not far to migrate.

Sorry, I don't quite get what you mean there. Are you suggesting I remove the 6 pin header and only use the ISP header for programming?
Logged

Global Moderator
Boston area, metrowest
Offline Offline
Brattain Member
*****
Karma: 549
Posts: 27419
Author of "Arduino for Teens". Available for Design & Build services. Now with Unlimited Eagle board sizes!
View Profile
WWW
 Bigger Bigger  Smaller Smaller  Reset Reset

What I meant was:
"So why not just load your sketch with an AVR ISP using File:Upload Using Programmer?"
Left out a word.
Keep the ISP header for loading future versions of the sketch.
Logged

Designing & building electrical circuits for over 25 years. Check out the ATMega1284P based Bobuino and other '328P & '1284P creations & offerings at  www.crossroadsfencing.com/BobuinoRev17.
Arduino for Teens available at Amazon.com.

Offline Offline
Newbie
*
Karma: 0
Posts: 19
View Profile
 Bigger Bigger  Smaller Smaller  Reset Reset

Hi guys,

I cant believe I forgot this part, a RTC!

http://www.ladyada.net/images/logshield/logschemv1.png

That schematic has a RTC and the same SD card reader as me, will copying it work?

Thanks,
Totara
Logged

nr Bundaberg, Australia
Offline Offline
Tesla Member
***
Karma: 130
Posts: 8620
Scattered showers my arse -- Noah, 2348BC.
View Profile
WWW
 Bigger Bigger  Smaller Smaller  Reset Reset

Yes I think so, if the card holder is the same.
______
Rob
Logged

Rob Gray aka the GRAYnomad www.robgray.com

Global Moderator
Boston area, metrowest
Offline Offline
Brattain Member
*****
Karma: 549
Posts: 27419
Author of "Arduino for Teens". Available for Design & Build services. Now with Unlimited Eagle board sizes!
View Profile
WWW
 Bigger Bigger  Smaller Smaller  Reset Reset

Yes. Use this brand of '125
http://www.digikey.com/product-detail/en/74AHC125S14-13/74AHC125S14-13DICT-ND/4505054
Has 5V tolerant inputs when powered from 3.3V.
Logged

Designing & building electrical circuits for over 25 years. Check out the ATMega1284P based Bobuino and other '328P & '1284P creations & offerings at  www.crossroadsfencing.com/BobuinoRev17.
Arduino for Teens available at Amazon.com.

Pages: 1 [2]   Go Up
Jump to: