The TD1204 is the GPS & Accelerometer version of the sigfox Telecom Design chip. After a previous post about the use of the accelerometers (here) I’m describing how to use the GPS module.
The embedded GPS is based on a UBX G7020 chip. This chip will give you the date, time, longitude, latitude, altitude, speed and direction of the device when activated.
Read more for programming details
The Telecom Design TD 1204, used on Sigfox network have a builtin 3 axis accelerometer and a lack of documentation as usual… By the way, here is the result of my searches to make it work.
Basically, the provided libraries makes it easy to use, in the setup part you have to initialize the accelerometers and in the main loop you have to run a TD_ACCELERO_Process(); method to monitor the IRQ and call your callback function to read the data.
It means that the accelerometers is not automatically waking up the device but managed during the 32KHz wakeup look.
The next part is detailing how to use it.
I just finished a program started a couple of month ago. When I stared to it, I had a hard work to find how to sample a group of 256 values at 32Khz with the EFM32 device embedded in the Telecom Design TD1204 / TD1208 used for my SigFox project. This post details how to do this task
2 TD1208 configured as RF Lan
TD1208, SigFox chips, include a RF LAN fonction, this allow you to communicate between different TD1208 chip, locally, without using the SigFox network. This is really interesting if you have a network of sensor, you can connect them this way to a gateway. This gateway will then transmit the information to the SigFox network to reach your IoT service.
This post will describe how the rf_lan work and how to implement it.
I’m not fully sure I implement it the right way as the given example are really poor, the documentation is a mess and the source code of this part is not accessible… More over, my feeling is that this part of the SDK is still running bugs. What I mean is that in a future post you should find an update and a better way to do it than the one I’m going to describe. By-the-way, what is here is working, have fun with it !
You may had some problem to reflash your TD1208 once you load the blink example or your own code in the device. This is because you need to reset the device to reach the firmware upgrade procedure during boot procedure.
On of the way to do it is to perform a hard reset putting Reset pin to ground during TDLoader Sync process. The other way is to add some lines in your code to create a soft reset. Here is an example on howto do it :
void TD_USER_Setup(void)
{
// Initialize the LEUART
init_printf(TD_UART_Init(9600, true, false),
TD_UART_Putc,
TD_UART_Start,
TD_UART_Stop);
}
void TD_USER_Loop(void)
{
while ((c = TD_UART_GetChar()) >= 0) {
NVIC_SystemReset();
}
}
When the loader is waiting for the bootloader sequence, it send communication over the serial line. In this example, when a such communication is detected, the system is calling a soft reset, starting the boot sequence and as a consequence the firmware upgrade automatically.
This tutorial is describing how to create a new SigFox project based on the given SDK version 4-0-0. Read the full post to get the details.
Pir sensor
In a previous blog post I described how I built a PIR sensor connected to Internet, based on the use of a Raspberry Pi device. As you can read in this previous post, the solution have a certain number of complexities like requiring a power supply, a 3G modem …
As it was originally planed to be done, here is the design of the same product, based on a SigFox device. This is really interesting to demonstrate the differences and the advantages of this technology. Let’s review how to built it !
In a previous post about SigFox technology, I told I will measure the power consumption to see if the device can be use with a battery easily. And what I can say is that they have made a great job on power saving with this device.
What I measure (with my really low cost multi-meter) is a standby consumption of 2uA and a transmission power of 45mA. The transmission of a message is not depending on the size of the message and is about 7s. As you can transmit up to 1 message every 15 minutes, the communication consumption is an average of 0,35mA/h.
Assuming battery from 750mA to 2500mA this is an autonomy from 4 months to 10 months. It’s a really interesting duration on battery and not comparable with a 3G communication system.
Now … testing is finish … I’ll start to implement a first POC for a project !
Hack fun !