Nuttx v2 and TFMini Lidar - possible wrong port?

ChrisHughes · June 2, 2018, 9:35pm

I’m trying to get a TFMini Lidar sensor to connect to a Pixfalcon flight controller via the telem port.

On startup, tfmini reports errors.

nsh> tfmini info
state @ 1000a850
Using port '/dev/ttyS6'
tfmini_read: 3 events, 274445us elapsed, 91481us avg, min 61380us max 142540us 44453.605us rms
tfmini_com_err: 3 events
poll interval:  10 ticks
report queue 2/64 (2/2 @ 1000bb70)

A couple of concerns here are:

The px4fmu-v2 board definition has the Telem1 port listed as a different device.

https://pixhawk.org/users/wiring

As can be seen in that link Telem 1 (pixfalcon only has Telem1, not Telem2), it should be /dev/ttyS1.

In my FC parameters, SYS_COMPANION is set to 0

When I attempt to do the following:

tfmini stop
tfmini start -d /dev/ttyS1

the flight controller crashes and immediately reboots with no error messages.

Could the default baud rate also be an issue, the TFMini expects 115200, the Pixfalcon defaults to 57600.

Please can you advise on next best steps for resolving this.

Zhengtian_Ma · August 31, 2018, 3:03am

hi, did you manage to solve the problem?
I am using tfmini with pixhawk 1 and have similar probelm

ChrisHughes · August 31, 2018, 4:49pm

Yes, this did solve one of the problems we were having with the device. We eventually abandoned NuttxV2 because the duty cycle of the various sensors made it too slow to hover in the air.

To get this working on NuttxV2 we modified the firmware changing file rc.sensors in ROMFS/px4fmu_common/init.d

In there you will find a series of if statements determining what tfmini start command is run on boot.

github.com

PX4/Firmware/blob/master/ROMFS/px4fmu_common/init.d/rc.sensors#L450


#!/bin/sh
#
# Standard startup script for sensor drivers.
#
# NOTE: Script variables are declared/initialized/unset in the rcS script.
#


if ! ver hwcmp AEROFC_V1 OMNIBUS_F4SD
then
	if ! ver hwcmp BITCRAZE_CRAZYFLIE
	then
		# Configure all I2C buses to 100 KHz as they
		# are all external or slow
		fmu i2c 1 100000
		fmu i2c 2 100000
	fi


	# External SPI
	ms5611 -S start


	# Internal SPI (auto detect ms5611 or ms5607)
	ms5611 -T 0 -s start


	# Blacksheep telemetry
	bst start


	adc start
fi


###############################################################################
#                           Begin Optional drivers                            #
###############################################################################


if [ ${VEHICLE_TYPE} = fw -o ${VEHICLE_TYPE} = vtol ]
then
	if param compare CBRK_AIRSPD_CHK 0
	then
		sdp3x_airspeed start -a


		# Pixhawk 2.1 has a MS5611 on I2C which gets wrongly
		# detected as MS5525 because the chip manufacturer was so
		# clever to assign the same I2C address and skip a WHO_AM_I
		# register.
		if [ $BOARD_FMUV3 = 21 ]
		then
			ms5525_airspeed start -b 2
		else
			ms5525_airspeed start -a
		fi


		ms4525_airspeed start -a


		ets_airspeed start -a


	fi
fi


if param compare SENS_EN_BATT 1
then
	batt_smbus start -X
fi


# Sensors on the PWM interface bank
if param compare SENS_EN_LL40LS 1
then
	if pwm_input start
	then
		ll40ls start pwm
	fi
fi


# Lidar-Lite on I2C
if param compare SENS_EN_LL40LS 2
then
	ll40ls start i2c
fi


# mb12xx sonar sensor
if param greater SENS_EN_MB12XX 0
then
	mb12xx start -a
fi


# pga460 sonar sensor
if param greater SENS_EN_PGA460 0
then
	pga460 start
fi


# Lightware i2c lidar sensor
if param greater SENS_EN_SF1XX 0
then
	sf1xx start -a
fi


# Heater driver for temperature regulated IMUs.
if param compare SENS_EN_THERMAL 1
then
	heater start
fi


# Teraranger one tof sensor
if param greater SENS_EN_TRANGER 0
then
	teraranger start -a
fi


###############################################################################
#                            End Optional drivers                             #
###############################################################################


# Wait 20 ms for sensors (because we need to wait for the HRT and work queue callbacks to fire)
usleep 20000
sensors start

As long as SYS_COMPANION=0 then this will be the boot line

tfmini start -d /dev/ttyS2

The port can be changed on that line then the firmware recompiled.