I found an older post /node/2119 with a link to this site (http://profmason.com/?page_id=106) which i have been looking at for a while. I somewhat understand the addressing, however the electronics part is a bit confusing. I know what pins 1-4 are grounded with pins 6 and 7 hooked up to the i2c sda and i2c scl pins (in that respective order) on the picaxe, in my case pins 23 and 18. IF I got all of that right, I’m wondering how (physcially) you’re able to hook up more EEPROMs on the same line. I understand the adressing part, however the electronics part is a bit sketchy.
If you hook up more than one
If you hook up more than one eeprom to the same I2C bus, you need to assign them two different addresses. If you look at the datasheet (http://www.alldatasheet.com/datasheet-pdf/pdf/157284/XICOR/X2402.html), you can see that pin 1-3 is the address selector. For the first eeprom, connect all three to ground. For the second, connect 1 to +5V and 2+3 to gnd etc. If you look at Figure 4, you can see what pins connected to +5V/gnd will get you which address.
argh just after I soldered
argh just after I soldered both in, well at least ill have something to work on later. Thanks for the info.
Icon --for a couple bucks you can make this very simple…
I started with making my own boards for the EEPROMS on walter, however I switched to these and never looked back… (I’m sure you can find it in the US for less than 10 bucks.) It is a super-simple board, usally used for the picaxe data logging kit but can be very easily used as a stand-alone unit. --It is just +, gnd, sda and scl. It has room for 7 eeproms and they are already addressed for you. With the i2cslave command, the last 3 numbers will correspond to any of the 7 chips you want to talk to… I.e. 000, 001, 010, 110 etc.
This is really a great, cheap board and solves a bunch of mistakes you could make… The only thing is that the pull-up resistors on each of the sda and scl lines are not included on the board -you have to have them on the main board. That’s it.