# Read write eeprom i2c

**URL:** <https://forum.xod.io/t/read-write-eeprom-i2c/1380>\
**Category:** Uncategorized\
**Created:** [November 17, 2018, 11:50am UTC](https://forum.xod.io/t/read-write-eeprom-i2c/1380 "2018-11-17T11:50:11Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![cesars](https://avatars.discourse-cdn.com/v4/letter/c/f05b48/32.png) [@cesars](https://forum.xod.io/u/cesars)\
**Post date:** [November 17, 2018, 11:50am UTC](https://forum.xod.io/t/read-write-eeprom-i2c/1380/1 "2018-11-17T11:50:11Z")

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I want to try to read or write an i2c memory, how do I select the address to read or write? requets asks for a byte amount but does not specify which, nor do I know how to select a memoria sector to read or write.  
I think that is missing in i2c or else it is used, I have created the device nodes, but I can not conclude with this part

The address goes in one of these two sectors (red)? and the first write (yelow), is the one that indicates reading or writing to the device or what is its function?

 ![eeprom_dir](https://canada1.discourse-cdn.com/flex027/uploads/xod/original/1X/adbbfaa1beab6bf4ed26087945568ca9bcedde58.png)

 ![eeprom](https://canada1.discourse-cdn.com/flex027/uploads/xod/original/1X/8f9f14d6379fe477cc6f6db281577c44065c44bd.png)

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**Author:** ![nkrkv](https://yyz1.discourse-cdn.com/flex027/user_avatar/forum.xod.io/nkrkv/32/8_2.png) [@nkrkv](https://forum.xod.io/u/nkrkv)\
**Post date:** [November 20, 2018, 4:07pm UTC](https://forum.xod.io/t/read-write-eeprom-i2c/1380/2 "2018-11-20T16:07:53Z")

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The `begin-transmission`, `write-byte`, and `end-transmission` nodes are 1-to-1 projection of Arduino’s `Wire` object methods. So, to send three bytes to a device at the specific address you build a chain of:

- `begin-transmission` (and pass the destination `ADDR` once there)
- `write-byte` to send the first byte within the transmission begun
- `write-byte` for the second byte
- `write-byte` for the third
- `end-transmission` to finalize the transmission

Am I understood you correctly?

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**Author:** ![cesars](https://avatars.discourse-cdn.com/v4/letter/c/f05b48/32.png) [@cesars](https://forum.xod.io/u/cesars)\
**Post date:** [November 20, 2018, 4:10pm UTC](https://forum.xod.io/t/read-write-eeprom-i2c/1380/3 "2018-11-20T16:10:20Z")

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Thanks, I’m going to try