# I2C scanner returns all addresses, despite pullup resistors **URL:** \ **Category:** Peripherals\ **Tags:** i2c, evb-amb82, rtl8735b\ **Created:** [February 28, 2025, 12:08pm UTC](https://forum.amebaiot.com/t/i2c-scanner-returns-all-addresses-despite-pullup-resistors/3867 "2025-02-28T12:08:06Z")\ **Posts on this page:** 13\ **Page:** 1
**Author:** ![Barryn56](https://avatars.discourse-cdn.com/v4/letter/b/8491ac/32.png) [@Barryn56](https://forum.amebaiot.com/u/Barryn56)\ **Post date:** [February 28, 2025, 12:08pm UTC](https://forum.amebaiot.com/t/i2c-scanner-returns-all-addresses-despite-pullup-resistors/3867/1 "2025-02-28T12:08:06Z")
Hello, newbie here. Just trying to get a battery-backed RTC connected to an AMB82-mini, so started with the I2CScanner. As it returns all addresses with nothing attached, I put in 2 pull up resistors (1.2k) on SDA and SCL (pins 12 and 13). However, the voltage across the resistors is zero, indicating an open circuit on those pins(?) Any comments would be appreciated. Alternatively, can a back up battery be installed for the internal RTC, so it keeps time after main power is cut? ---
**Author:** ![KevinKL](https://sea2.discourse-cdn.com/flex016/user_avatar/forum.amebaiot.com/kevinkl/32/2632_2.png) [@KevinKL](https://forum.amebaiot.com/u/KevinKL)\ **Post date:** [March 4, 2025, 9:16am UTC](https://forum.amebaiot.com/t/i2c-scanner-returns-all-addresses-despite-pullup-resistors/3867/2 "2025-03-04T09:16:10Z")
Hi @Barryn56 , May I clarify with you on “it returns all addresses with nothing attached”, does it mean it returns a random address of an I2C device? I have tested a few I2C examples in our Arduino SDK including I2CScanner, they are working fine. I could not reproduce your issue as there’s no I2C address returned when nothing is attached. The voltage across the pull-up resistor should be 0 when there is no current flowing through it, it is behaving normally as a pull-up resistor, which is to supply external Vcc to the input pin. Unfortunately, we can’t install a battery for the internal RTC, apologize for the inconvenience caused. Thank you. ---
**Author:** ![Barryn56](https://avatars.discourse-cdn.com/v4/letter/b/8491ac/32.png) [@Barryn56](https://forum.amebaiot.com/u/Barryn56)\ **Post date:** [March 4, 2025, 10:26am UTC](https://forum.amebaiot.com/t/i2c-scanner-returns-all-addresses-despite-pullup-resistors/3867/3 "2025-03-04T10:26:17Z")
Hello Kevin, and thanks so much for your reply. As other people have mentioned, the I2C scanner just lists all possible addresses, and this led me to a comment that the I2C needs pull up resistors. I put 2 resistors (tried different values) on the 5V line, but it made no difference, the scanner still returns a total list of values. My plan forward is to use the SPI interface and a suitable RTC. This is an absolutely great product though! Personally, I wouldn’t use the NN chip, as I’d just use it for data acquisition and then process offline. I’d like to be able to put text (from the RTC) on the recorded video while maintaining 30fps, so looking into that now. Regards, Barry ---
**Author:** ![Kelvin\_Huang](https://sea2.discourse-cdn.com/flex016/user_avatar/forum.amebaiot.com/kelvin_huang/32/2130_2.png) [@Kelvin\_Huang](https://forum.amebaiot.com/u/Kelvin_Huang)\ **Post date:** [March 6, 2025, 1:26am UTC](https://forum.amebaiot.com/t/i2c-scanner-returns-all-addresses-despite-pullup-resistors/3867/4 "2025-03-06T01:26:25Z")
Hi @Barryn56, Can I check what SDK version are you using? Thank you. ---
**Author:** ![Barryn56](https://avatars.discourse-cdn.com/v4/letter/b/8491ac/32.png) [@Barryn56](https://forum.amebaiot.com/u/Barryn56)\ **Post date:** [March 6, 2025, 2:10am UTC](https://forum.amebaiot.com/t/i2c-scanner-returns-all-addresses-despite-pullup-resistors/3867/5 "2025-03-06T02:10:54Z")
Hi Kelvin, I am just using the Arduino (IDE 2.3.4), which I presume has the latest standard SDK(?). Let me know if there’s a sketch which will provide further details, or anywhere I should look to ensure the right SDK is being used. Best regards, Barry ---
**Author:** ![Kelvin\_Huang](https://sea2.discourse-cdn.com/flex016/user_avatar/forum.amebaiot.com/kelvin_huang/32/2130_2.png) [@Kelvin\_Huang](https://forum.amebaiot.com/u/Kelvin_Huang)\ **Post date:** [March 6, 2025, 2:13am UTC](https://forum.amebaiot.com/t/i2c-scanner-returns-all-addresses-despite-pullup-resistors/3867/6 "2025-03-06T02:13:46Z")
Hi @Barryn56, Can you check your boards manager? My current version is 4.0.9-build20250117. ![image](https://us1.discourse-cdn.com/flex016/uploads/ameba/original/2X/f/f9258bd6ef425250f8ec165c245ccda3b54acadf.png) ---
**Author:** ![Barryn56](https://avatars.discourse-cdn.com/v4/letter/b/8491ac/32.png) [@Barryn56](https://forum.amebaiot.com/u/Barryn56)\ **Post date:** [March 6, 2025, 2:27am UTC](https://forum.amebaiot.com/t/i2c-scanner-returns-all-addresses-despite-pullup-resistors/3867/7 "2025-03-06T02:27:06Z")
Hi, well mine is only 4.0.5, so I shall see about getting the latest version, as there’s no ‘update’ option shown. ![image](https://us1.discourse-cdn.com/flex016/uploads/ameba/original/2X/7/71f0f287276c36d7c1b53ce667ae56208d59506f.jpeg) ---
**Author:** ![Barryn56](https://avatars.discourse-cdn.com/v4/letter/b/8491ac/32.png) [@Barryn56](https://forum.amebaiot.com/u/Barryn56)\ **Post date:** [March 6, 2025, 2:31am UTC](https://forum.amebaiot.com/t/i2c-scanner-returns-all-addresses-despite-pullup-resistors/3867/8 "2025-03-06T02:31:59Z")
OK, so I did an update (download) to 4.0.8. Will recheck. Thanks, Barry ---
**Author:** ![Barryn56](https://avatars.discourse-cdn.com/v4/letter/b/8491ac/32.png) [@Barryn56](https://forum.amebaiot.com/u/Barryn56)\ **Post date:** [March 6, 2025, 4:49am UTC](https://forum.amebaiot.com/t/i2c-scanner-returns-all-addresses-despite-pullup-resistors/3867/9 "2025-03-06T04:49:15Z")
Hi Kelvin, so I upgraded, but the problem remains, and I am now getting a lot of error messages about missing files: ![image](https://us1.discourse-cdn.com/flex016/uploads/ameba/original/2X/e/edbe19f7a4c0d6b5f8aa9da865625029f6166c5b.jpeg) ---
**Author:** ![Kelvin\_Huang](https://sea2.discourse-cdn.com/flex016/user_avatar/forum.amebaiot.com/kelvin_huang/32/2130_2.png) [@Kelvin\_Huang](https://forum.amebaiot.com/u/Kelvin_Huang)\ **Post date:** [March 6, 2025, 6:08am UTC](https://forum.amebaiot.com/t/i2c-scanner-returns-all-addresses-despite-pullup-resistors/3867/10 "2025-03-06T06:08:05Z")
Hi @Barryn56, It seems like you are not running the I2C Scanner example from our SDK. Can you try to reinstall the SDK too? Thank you. ---
**Author:** ![Barryn56](https://avatars.discourse-cdn.com/v4/letter/b/8491ac/32.png) [@Barryn56](https://forum.amebaiot.com/u/Barryn56)\ **Post date:** [March 6, 2025, 6:36am UTC](https://forum.amebaiot.com/t/i2c-scanner-returns-all-addresses-despite-pullup-resistors/3867/11 "2025-03-06T06:36:36Z")
Hi, and thanks for the continuing support. I found the issue with the new errors is due to the User folder name. Mine had a full stop and other text after the initial name. It seems the new version doesn’t read the whole name, just the text up to the full stop. I’ve gone into the PC and changed the name, so I will see if that fixes the file access, but I have to re-install the Arduino IDE, as it is now not starting. Then I will look at the I2C scanner sketch, which I got from the internet. Regards, Barry ---
**Author:** ![Kelvin\_Huang](https://sea2.discourse-cdn.com/flex016/user_avatar/forum.amebaiot.com/kelvin_huang/32/2130_2.png) [@Kelvin\_Huang](https://forum.amebaiot.com/u/Kelvin_Huang)\ **Post date:** [March 6, 2025, 8:13am UTC](https://forum.amebaiot.com/t/i2c-scanner-returns-all-addresses-despite-pullup-resistors/3867/12 "2025-03-06T08:13:33Z")
Hi @Barryn56, Please refer to this guide here. [I2C – Scan I2C devices – Realtek IoT/Wi-Fi MCU Solutions](https://www.amebaiot.com/en/amebapro2-arduino-i2c-scan/) Thank you. ---
**Author:** ![Barryn56](https://avatars.discourse-cdn.com/v4/letter/b/8491ac/32.png) [@Barryn56](https://forum.amebaiot.com/u/Barryn56)\ **Post date:** [March 7, 2025, 2:48am UTC](https://forum.amebaiot.com/t/i2c-scanner-returns-all-addresses-despite-pullup-resistors/3867/13 "2025-03-07T02:48:34Z")
Hi Kelvin, the upgrade to the latest version of boards, etc., has worked. Now finds no I2C boards when empty. Thanks again for your great support. Regards, Barry