TD1508 is the FCC version of the TD1208, they are pin to pin compatible and based on the same SDK so converting an object working on a TD1208 sounds easy. Practically speaking there are some preparing steps because of some tiny bugs to solve.
Let see how to port a Telecom Design existing firmware for TD1208 to TD1508 (from ETSI to FCC).
I recently bought an AirSpy mini SDR (Software defined radio) dongle. Understand, it is a radio scanner you connect on your computer able to analyze radio communications on a large frequency range from 24MHz to 1,7HGz. The main difference between this SDR and the low cost one based on RTL 2832 + R820T is the spectrum view up to 6Mhz, the TCXO working with 0,5ppm and globally the quality of the solution and the availability of libraries. What is presented here is also valid for RTL based dongle.
With this tool you can see what is happening on the radio frequencies in real time, compare power, listen radio … This post is presenting how to install it and use it on windows & Mac Os X.
I’m using different GPS antennas with different price, size and gain and I had never compared the result in a real live test. So now it is done and the result are good to share.
My test condition are quite bad and we can’t really consider this as a scientific bench but, experimentally it sounds like a real life test.
So the test is to connect an antenna to a TD1204 with a GPS code on it and test the time it makes to fix the position and get some note about signal level, satellites in view… I used in fact 2 TD1204 : one with a reference antenna to ensure we have equivalent condition from one test to the others. The tests are made indoor where the sensitivity is an important factor. This post detail the results.
After making my kit on my own, I finally got the official Telecom Design TD1204 kit (thank you TD) There is no big issues to use it once you have the right entry point, but as I had some email exchange with support to be fully ready for using it, I’m prefer to share some words with you on what to do and how it works.
Basically, the TD kit is an EFM32 Tiny Gecko Starter kit (STK3300) with some little modifications. The EFM kit have two interesting functions : in own a Jlink JTAG/SWD programming and debugging interface and its EFM32 MCU can be use to monitor power consumption with precision.
For a certain IoT design I had to understand how my box design impacts the temperature of the circuit and of my battery. To understand how it works in the real environment, I made a small circuit based on an Arduino Nano to get temperature with 6 different sensors and store it in a flash memory for later use.
This post describes the way to do this multi-temperature sensor platform. Code is under GPL.
After writing a post about my experience with LiPo Batteries I’m now proposing a post about NiMh. LiPos are good batteries : not expensive with a good energy density, really easy to manage for charging. For these reason they are used in many electronic designs.
But in some applications they are not enough stable, this is as an example the case for an automotive use where the internal temperature of a car can reach higher temperature than 65°C. This is the limit for LiPos. In my experiences I had some having been destroyed due to warm temperature.
NiMh is not an optimal solution but you can find some batteries capable to support 85°C and resist to +130°C before being destroyed and have a fire risk. Varta V500HT is a good example of battery for a such use.
NiMh is less easy to use than LiPos, this post is detailing my experience.
This week I had to play with some TFT screen for RapberryPi for making a prototype for a local company. You can find many TFT screen on Internet but most of them are not coming with a nice fresh documentation for being use and it is kickly a mess to get it start with them. I ordered different one having the same 3.2” size matching my need and got 2 of them for starting tests.
This post details how to use a such screen for displaying a picture on it from a console line.
Measuring a pulse duration in a pulse train was my last week headache with the TD1208 and the not so well documented EFM32. Basically, my objective was to activate a timer on a pulse train to measure the duration of the pulse. This duration was measured about 100uS and occurred at 1 Hz.
My choice was to rise an interrupt on each signal front (raising and falling) and measure the duration between the two first interrupt call. Some reset function ensure we are measuring the low state duration (100uS) not the high state duration (1s). This part will not be described here. The purpose of this post is to describe the main hole I fallen in.
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