C: Get IMU v2 configuration

[generalazure]

Hello,
I can connect to and get various sensor data from my IMU v2 (with realistic values), but I run into trouble when I try to query the configuration. Specifically, calling imu_v2_get_sensor_configuration sets all the output values to 204 (which is invalid for all of them and suspiciously looks like uninitialized memory), then indicates success by returning 0.
I had a quick glance at the code, but cannot quite tell where these values are supposed to be copied: The single memcpy in ip_connection::device_send_request appears to only deal with the header (copies a chuck of size response_packet.header.length, which is always 8 bytes for me).

[photron]

Are you sure that you're using the correct UID for your IMU Brick 2.0?

[generalazure]

I am using the same UID that is shown in Brick Viewer and that works fine for getting sensor measurements. I've created a minimal example:

IPConnection ipcon;
ipcon_create(&ipcon);
IMUV2 imu;
imu_v2_create(&imu, "6QF9YH" , &ipcon);
int ret = ipcon_connect(&ipcon, "localhost", 4223);
uint8_t magRate, gyroRange, gyroBandwidth, accRange, accBandwidth;
ret = imu_v2_get_sensor_configuration(&imu, &magRate, &gyroRange, &gyroBandwidth, &accRange, &accBandwidth);
int8_t temp;
ret = imu_v2_get_temperature(&imu, &temp);

Executing the code above in VS2013 x64 debug mode gives me a correct temp (currently 31), but 204 for all config values. The return value of all 3 calls is 0.

[photron]

I tested this with VS 2015 and it works for me.

Are you using the latest C/C++ bindings (2.1.15) and the latest IMU Brick 2.0 firmware (2.0.8)? If not, does ist make a difference if you update?

Could you test the following example with the modified ip_connection.c from this gist and show me its output?

https://gist.github.com/photron/fc3af20746305ad8ae46c4182e9f237f

#include <stdio.h>

#include "ip_connection.h"
#include "brick_imu_v2.h"

int main(void) {
	IPConnection ipcon;
	ipcon_create(&ipcon);
	IMUV2 imu;
	imu_v2_create(&imu, "6QF9YH" , &ipcon);
	int ret = ipcon_connect(&ipcon, "localhost", 4223);
	printf("A %d\n", ret);
	uint8_t magRate, gyroRange, gyroBandwidth, accRange, accBandwidth;
	ret = imu_v2_get_sensor_configuration(&imu, &magRate, &gyroRange, &gyroBandwidth, &accRange, &accBandwidth);
	printf("B %d %d %d %d %d %d\n", ret, magRate, gyroRange, gyroBandwidth, accRange, accBandwidth);
	int8_t temp;
	ret = imu_v2_get_temperature(&imu, &temp);
	printf("C %d %d\n", ret, temp);
	imu_v2_destroy(&imu);
	ipcon_destroy(&ipcon);
	return 0;
}

The modified IP connection will dump the raw requests and responses. The output should look similar to this.

A 0
S 8: 48 22 56 197 8 42 40 0 -> 0
R 13: 48 22 56 197 13 42 40 0 5 0 7 1 3 -> 0
B 0 5 0 7 1 3
S 8: 48 22 56 197 8 4 56 0 -> 0
R 9: 48 22 56 197 9 4 56 0 36 -> 0
C 0 36

[generalazure]

Good call about the firmware version, updating from 2.0.4 to 2.0.8 solved the issue. Response packet length is 5 bytes more now and the contained values make sense. Guess I should run updates more often.
Anyway, thanks for the help :)

[photron]

The imu_v2_get_sensor_configuration function was added in firmware version 2.0.5. Therefore, firmware 2.0.4 should respond with an error and the C/C++ bindings should return E_NOT_SUPPORTED (-10). But there was a bug in the firmware, that made the Brick not correctly report an error in this case. That's why imu_v2_get_sensor_configuration returned 0, while it should actually have returned E_NOT_SUPPORTED (-10). This bug was fixed a while ago.

Your problem was trying to call imu_v2_get_sensor_configuration with a firmware that does't have that function yet, but also has a bug that makes it report this incorrectly. So nothing to fix here actually.