GPS module pinouts. Please

[bakerpip]

Hi All, Anyone still flying Chroma or know much about it? I have two and am wondering about using parts of one to build a new drone. Here's what I'm wondering.
1. Can the st10 receive vtx and telemetry/ RC control over a reasonable distance?
2. Might I be able to substitute a newer flight controller?
3. Anyone know the pinouts of the GPS module? I've worked out 4.5v and ground just trying to guess tx Rx and scl SDA?

 

[h-elsner]

1. What is reasonable distance? Chroma manual says 800m. I think this is nearly that, ST10 / SR24 can perform, maybe a bit more with a better antenna set. I would not count for more that 1km.
2. PX4 autopilot has a SW module for SR24 but as far as I know nobody has build a FW for newer FCs with that.
Another idea is the SR24 to SBUS converter from @dylanfm - discussed here some time ago.
3. I don't know. Because Chroma is predecessor of Q500 try pinout of Q500 GPS module. There is a good chance that is the same. Rx/Tx is for GPS, SDA/SCL is for pressure sensor (or maybe compass chip as it was made from Typhoon H on).

Here as example the compensation module pinout of Q500 vs. Typhoon H.


br HE

 

[bakerpip]

Thanks for the information. My GPS mast does include the compass so looks like it's the typhoon h pinouts.
Please clarify what is the SR24?

 

[h-elsner]

SR24 is the ZigBee receiver used in Chroma, Q500, Typhoon H, H+, H3 ... (many Yuneec drones use it). SR24 is compatible to RCs ST10, ST10+, ST16, ST16S, ST24.

 

[bakerpip]

Thanks but how do I connect my SR 24 to a flight controller preferably a generic F405 type FC or maybe a pixhawk 4?

 

[bakerpip]

I now tested my Chroma GPS mast using a cable to serial on a FT232RL serial to usb with Ublox ucenter2 software and it works well getting a 3d fix quickly indoors. In case it helps anyone else I took a picture of the cable designations.

 

[h-elsner]

SR24 has a UART 3.3V level connection. Data sent/received via messages. Message format: SR24_decode/Doc/UART_ST24_raw.ods at main · h-elsner/SR24_decode

Pinout older version with connector:

Pinout newer version with wires:

br HE

 

[bakerpip]

So if I can connect my SR24 to a pixhawk4 running ardupilot or PX4, do I have the potential to still use the video output from the cgo3 on the st10+ and use the escs and motors from the chroma

 

[h-elsner]

The video transmission and camera settings are complete independent from RC connection to flight controller. It is a different channel using 5GHz WiFi, video stream uses RTSP and camera settings are done via CGI commands using HTTP. CGO3 camera will always work with ST10 or any othe device that have 5GHz WiFi, no matter what drone/FC is bound to SR24 or not.
Only the gimbal (camera tilt) is controlled by flight controller via 2.4GHzZigBee connection.

The protocol to control the ESCs is unknown. I doubt that ESCs will work with Pixhawk FC.

br HE

 

[bakerpip]

Can anyone help me with compass setup from my Chroma GPS/compass module which appears to be the same as that in the yuneec h series. I have GPS working well to my FC but the sda/scl connections don't appear as a compass to my FC. The module works in the chroma and the FC recognises the compass on it's sda/scl port if I use a different GPS/compass module. Hence my confusion. I've tried swapping the sda and scl connections in case I have those mixed up to no avail.

 

[WTFDproject]

Can anyone help me with compass setup from my Chroma GPS/compass module which appears to be the same as that in the yuneec h series. I have GPS working well to my FC but the sda/scl connections don't appear as a compass to my FC. The module works in the chroma and the FC recognises the compass on it's sda/scl port if I use a different GPS/compass module. Hence my confusion. I've tried swapping the sda and scl connections in case I have those mixed up to no avail.

I know it might be a dumb question, but are you sure the compass that is not being recognized is a working compass?

 

[bakerpip]

It works as a compass on my blade chroma. It is a spare blade module

 

[bakerpip]

I'm thinking this means the main board FC in the chroma incorporates pull up resistors between vcc and sda /scl on board. So they are not present in the module. If that's the case I can add the resistors within the modules case. I will check this out

 

[h-elsner]

Do you want to connect the GPS module to another flight controller or is it the Chroma that is not working? If you have another FC connected, which one?
There are a couple of compass modules. The FW of the FC needs to know which one and load the appropriate driver.
I know that Yuneec GPS modules can have two different compass chips:
- HMC5883 (most probably the one at Chroma module)
- IST8310
Which one is on your module? HMC has the numer L883 on the chip.

 

[bakerpip]

Thanks for your help? My compass is a chroma one and it is an L883 so I assume HMC. My FC I'm trying to connect to is a Speedybee f405 wing running arduplane 4.4 and it has the firmware for qmc5883 enabled which I think is the same. With a different GPS module with the 5883 compass installed the FC detects the compass but when I replaced that module with the chroma one on the same port the GPS works fine but the compass is not detected. This chroma module works on my Chroma and if I use the module from my spare chroma also known to be working it is not found by the FC.

 

[bakerpip]

Thanks for your help. Yes it's a Chroma GPS with the Hmc5883 compass connecting to Speedybee f405 wing with custom build arduplane firmware.
I've solved the issue now and got it working. Reflashing the FC firmware ensuring the 5883 driver was included and tweaking the compass parameters seems to have done the job.