Tagged: BLE

Quote I found on the back of a token - "ವಿಶ್ವಾಸವಿದ್ದರೆ ಪ್ರೀತಿ. ಪ್ರೀತಿಯಿದ್ದರೆ ಗೌರವ." Which roughly translates to "There is Love if there is trust. There is Respect if there is love" 4

Weekly Notes 03/2025

Time flies faster than we can think of. Nagarathna Memorial Grant – 2025 is open for applications; this is our eighth edition. When I started it, I didn’t think much about how it would turn out in a couple of years. So, there were no expectations. But it has grown into its own...

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Simple BLE Oximeter App using PHONK

In the past I would have used MIT AppInventor or Expo.io. Both have amazing ecosystems. It’s easy to build apps using them. But this time I wanted to use PHONK. I had used Protocoder before and had liked it. Also I have this idea of building small utility apps called applets (yes!), that...

Bluetooth Oximeter 0

Reverse Engineering A Bluetooth Low Energy Oximeter

Just as COVID-19 is spreading in Bangalore. I got an Oximeter which can measure SpO2. SpO2 is also called as oxygen saturation, According to Wikipedia Oxygen saturation is the fraction of oxygen-saturated hemoglobin relative to total hemoglobin (unsaturated + saturated) in the blood. The human body requires and regulates a very precise and...

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BLE Sending more than 20 Bytes of Data

Last year when I was designing the BLE App, one of the hurdle we faced was the packet size. I couldn’t send more than 20 bytes of data at once. So I had to created packets of 20 bytes and send them one by one, with some headers for packet information. On the...

Image Credit: Espressif Systems. ESP32 is created and developed by Espressif Systems. 1

ESP32 – BLE : Building an Echo Service GATT Server

As you would know I use ESP8266 in every possible way. It’s probably the cheapest board with Wifi chip built-in. When I heard about ESP32, it was a dream come true. ESP32 packs both Wifi and BLE in one single module for less than $10. Given the size of developer fan following 8266...

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Authenticating to BLE device Offline

Let’s say I have a Bluetooth Low Energy device which is a GATT server and is not connected to internet.  I have a phone which can connect to this BLE device, authenticate itself and do some data exchange. The problem I am trying to solve authentication. The condition is both BLE device and...