Freematics Forum

Hi is there any hardware specification guide available from freematics for V4?
What does blinking LED means/ does it indicate any data logging to SD card? ANy other real time ic available on board? how to change MEMS sensor data rate? range (+- g) ? Any help from administrator?
Why you can't provide even basic specifications to your customer? !!!!

I agree that some more information would be very helpful. I am also curious about the LED light.

What I would like to know is if there is a way to send commands directly to the GPS receiver. It seems that the board was designed to pass all of the OBD and GPS information through the STM32 unit. The Arduino code in the Freematics repository uses undocumented ASCII commands like "ATGPSON", "ATGRR", and "ATCLRGSM". Currently the only Google result for "ATCLRGSM" is the Freematics Github page, and this will post be the second. This suggests that the STM32 is running custom and/or closed-source software. There may not be much we can do without this code.

Here are some product pages and datasheets:

STM32F103C8

UBLOX M8030

UBLOX G7020

MPU 6050

ATMega 328P

Also, I took some good pictures of the board, on both sides. I might upload those later. In the meantime, here are the chip labels:

Thanks @mikebolt again.
These are my observations regarding hardware after using it for two weeks, will keep it updating, hope these will help you. Correct me if I am wrong.
1. STM32 and SD card are both on SPI bus.
2. OBD, GPS are connected to STM32 which is not accessible to reprogram
3. Since GPS data can be accessed no more than around 10Hz we can not increase the accelerometer frequency to log data on SD card , coz they both are using same SPI bus.(contn.......)

I went through the data sheets trying to figure everything out. I also asked Stanley a few questions. He told me that the LED indicates activity between the STM32 chip and the ATMEGA328P chip. The two are connected via SPI. I know that activity between them will occur in the initGPS method and whenever getGPSData or getGPSRawData are called. This explains why it blinks once at the start, and then continuously for the rest of the trip.

I suspect that GPS is not connected via SPI. The two pins it connects to on the STM32 are identified as supporting either I2C or USART, but not SPI.

I am not sure if the SD card is on the SPI bus or not.

There is an open set of pins for connecting to the SPI bus between the STM32 chip and the GPS connector.

It might be possible to reprogram the STM32 via the "J4" pins at the top of the schematic diagram. I have no idea.

I don't think the GPS is limiting the frequency of anything. If you disable GPS and OBD in the datalogger you should see MEMS data collected at a high frequency. There are "delay" calls throughout the code that slow things down also. In most cases they are necessary, but you might get a speedup by lowering the values a bit.

Thanks ,
Yes GPS is not connected via SPI.
Yes, SD card is on SPI bus because they mentioned it here, http://freematics.com/pages/products/freematics-one/ and whenever we log data on SD card LED goes ON. which supports your statement that LED indicates SPI bus activity.

J4 pins >Need to verify. I want comment from @stanley on this. I don't know how to tag him here!!!

GPS is limiting frequency > I am considering scenario where both GPS and MEMS data logging. Since GPS and SD card are on same bus, we can't write to SD card until GPS request frees SPI bus. I tried to log data when program is waiting for GPS data but it is just creating new empty file for every access of SPI bus.

One thing I couldn't figure out? > Is the STM32 firmware continuously reading GPS and storing GPS data in a memory or it reads GPS only on a request from ATmega ? Considering we have to wait till we get GPS data after sending request to STM32, STM32 reads GPS only on a request from ATmega. let me know your comments!!

I don't think there's any way to know that without the STM32 code. The ATGRR command only returns one GPS fix, although it looks like sometimes it returns both a GGA message and an RMC message.

I hope you keep experimenting with sampling while waiting for the GPS messages. The ~7Hz sampling is good enough for us. I'm not sure why you would get a bunch of empty SD files. You should try logging to the console with a laptop outside.

thanks..
How did you find that it returns both GGA and RMC? I always received RMC!!
Yeh, I can do it.

We have purchased ~30 freematics ONE+ B/H and we're wondering if we can reprogram their stm32f103 IC with SWD probe.

• Have you locked these ICs with readout/protection (RDP/PCROP)?
• Where is the code of the STM fw?

Any hint here?