Hi @scosgrove,

Thanks for the details.

On the DSP there is a dedicated HW block for each UART (similar for the UARTs connected to the application processor). All the UARTs supported on DSP have hardware FIFOs. Since you asked about the size:

DSP UART2 has 64-byte low level FIFO on RX DSP UART6, 7 have 128-byte low level FIFO on RX

When fifo is close to filling up, there is an ISR that triggers on the DSP which transfers the data from FIFO to other memory, and then the data propagates to the user. I wonder if there is some issue when fifo is read while another byte is incoming into fifo at the same time.

Which uart port are you using for this test?

I can do some testing with bursts of 70-250 byte packets. In the past we have tested continuous data transfers of several KB but not at high rates. Also, what baud rate are you using now?

Alex

@modaltb

Hey Travis,

Thank you very much for your explanation and for passing on the link.
I understand how it was done now.

I will consider what is the next possible option for the project.  
I appreciate your time.

Best Regards,
Leon

@I_Dwyer @Chad-Sweet Hello all, has this issue been solved in and particular version, we too are facing the same issue, on HS1 the voxl-mavlink server is initiating but we are not able to see any data from this port. We are right now on the 1.5.3 build. Pls provided more info on the same.

Which version of PX4 are you running on the Pixhawk and do you have a magnetometer connected? EKF2 is generally unhappy about about starting without a magnetometer in PX4 1.11 so we patched the PX4 firmware for Flight Core to get around this. In PX4 1.12 and newer the following PX4 parameter can be set to allow EKF2 to allow position mode without a GPS/Mag

## disable mag SYS_HAS_MAG 0 EKF2_MAG_TYPE 5

@modaltb hello, when will the next SDK release be available? Would love to the UARTs working for external FC. Thank you.