Extend 28x1 limitations??

A

AndersNyman

New Member
Hey!

I have bought a 28x1 microcontroller, and I am totally amazed of the simplicity and the possibilities!

I just post my project i´m working on in this thread: http://www.picaxeforum.co.uk/showthread.php?t=11653

But to go futher with my project I need to control up to maybe 10-20 servo motors at the same time and I also need much more memory. Is there any way to extend the 28x1 controller? Or do I need to buy a new one. If so, can you recommend one that can fulfil my needs?

I have search this forum, but havent found any good answers on this...

Cheers!
 
A

AndersNyman

New Member
Ok, so I need a "21 Channel Servo Controller" and a "PICAXE-18X microcontroller"? And it will work with my 28x1 board?

And at the same time I can connect a "I2C EEPROM" to my board?

Am I right?
 
B

BeanieBots

Moderator
Well there's no "board" which can do all that, but you could make one.
Be aware, you cannot extend the program space with EEPROM. You can only use it to store data. That data could however be sequences that are read in and then sent out to control the servos.
 
B

BeanieBots

Moderator
Before you go dashing off and buying loads of boards and chips, you only need a PICAXE which supports I2C (eg the 18X) and some I2C memory. You don't need a full blown datalogger board if you only want to read back a sequence of servo movements.
You could do 8 servos just with a 28X1 and an EEPROM chip.
The 21-servo board would give you a few more servos.

Getting a datalogger is not REQUIRED but if you don't feel comfortable making your own circuit it could be used as an expensive way of having an 18X with a little data memory.
 
W

westaust55

Moderator
BeanieBots said:
Before you go dashing off and buying loads of boards and chips, you only need a PICAXE which supports I2C (eg the 18X) and some I2C memory. You don't need a full blown datalogger board if you only want to read back a sequence of servo movements.
You could do 8 servos just with a 28X1 and an EEPROM chip.
The 21-servo board would give you a few more servos.

Getting a datalogger is not REQUIRED but if you don't feel comfortable making your own circuit it could be used as an expensive way of having an 18X with a little data memory.
Click to expand...
The AXE022 board will accept the 28X1 which AndersNyman already has and has an onboard socket of a EEPROM.
 
A

AndersNyman

New Member
Ok, so I can connect the SCL pin from the EEPROM to pin no 14 on my picaxe 28X and SDA to pin no 15.

How do I upload data to the I2C EEPROM? From the programming editor?


i found this scheme:


I am very thankful for the help you guys giving me!
 
hippy

hippy

Ex-Staff (retired)
AndersNyman said:
Ok, so I can connect the SCL pin from the EEPROM to pin no 14 on my picaxe 28X and SDA to pin no 15.
Click to expand...
That is correct. Both SCL and SDA will need pull-ups to +V ( as shown in the lower part of your diagram ), these would normally be 4K7. You also need to connect the other pins as shown. It is more common to connect A0, A1 and A2 to 0V, not an absolute necessity but can make things easier, but this will also depend on what make of I2C Eeprom you are using.

AndersNyman said:
How do I upload data to the I2C EEPROM? From the programming editor?
Click to expand...
The usual way is to write a PICAXE program which can load the I2C EEPROM and run that.
 
D

Dippy

Moderator
For data transfer, there are two usual ways.

1. As hippy says, write a PICAXE programme with your Data in it and get it to write to the EEPROM.
Then your subsequent PICAXE programme will read (and modify) where needed.

2. If you have a lot of data to write, then write a routine in your PICAXE code which can take data from your PC (e.g. a VB programme) and transfer it to the EEPROM. Your PICAXE+routine acts like the 'middle man'. That's how its done on one of the graphics firmware chips. It makes it very slick. So, in action: Click your PC App and the data ends up in the EEPROM. Handy for lots of Data or where Data are changed frequently.
Needless to say it also depends how much code space you have spare.

Or get a PICKit2.. just kidding ;)
 
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