The original DARwIn-OP Robot uses an on-board 1.6 GHz Intel Atom Z530 computer and a CM-730 ARM controller board. This controller board includes a 3-axis gyro, a 3-axis accelerometer and a Dynamixel bus to interface with the robot’s servos.
I intend to use an alternative electronics based on a more powerful ARM computer plus several peripherals. For the main computer, my current choice is the ODROID-XU which is a quad Cortex-A15 1.6GHz CPU with 2GB RAM.
Instead of using a controller board, I’ll be using a USB2AX to interface the Dynamixel servos and I’ll use I2C components for the gyroscope and accelerometer.
On the picture are shown the components that I already got and that I’ll be testing:
- I2C 12 bit 4 channels ADC (ADS1015 chip)
- I2C voltage-level translator (PCA9306 chip)
- I2C 10DOF with 3-axis gyro, 3-axis accelerometer, 3-axis compass, temperature and pressure sensors (L3G4200D, ADXL345, HMC5883L, BMP085 chips)
- Force sensing resistor (.1N to 100N)
- ODROID USB IO Board with GPIO/PWM/SPI/UART/I2C/ADC interfaces
- USB2AX Dynamixel interface
I’ll be using the native I2C interface I2C_0 that is available in the LCD connector (CON15) in the back of the ODROID-XU (the schematics are available through a customer email request to Hardkernel).
The LCD connector is an IPEX 40 pin with 0.5mm pitch. I got some a couple of cables from Ebay, but now I saw that Hardkernel (the maker of the ODROID) is also selling the cable. The pin configuration that I’ll be using for the I2C interface is:
- 4 – 1.8V
- 6 – SCL
- 7 – SDA
- 10 – GND
The ODROID-XU’s I2C interface is rated at 1.8V, so I’ll be using the PCA9306 to translate it to the rest of the I2C components which are rated at a higher voltage.
The DARwIn-OP requires a gyroscope and an accelerometer, but I am interested also in using the compass and the force sensors (through the AD converter) for a future version of the DARwIn-OP feet.
hi, I am a beginner of Darwin, and am going to participate in Robocup.
Can darwin-op2 robot be fitted with electronic compass? It have no I2C….
Could you please give me some advice, please:)
Hi,
Do you mean an original Darwin-OP2?
You could use an USB port and connect an USB IO board expansion such as these to have an i2c port:
http://www.hardkernel.com/main/products/prdt_info.php?g_code=G135390529643
or
http://www.tme.eu/en/details/mikroe-1985/development-kits-accessories/mikroelektronika/usb-i2c-click/
I would check for one that has drivers available for your platform first.
Then you can connect a i2c compass.
I don’t know if the Darwin-OP2 has any internal USB connector available, it would not be very pretty to have a USB cable connected on the back an going back in. I don’t know the camera wiring, I understand it is USB, sou you could tap in with a hub.
hi, your post like with my minithesis, i still confused to connecting accl+gyro value into framework, can you show your code modification in Darwin-OP framework? hahaha thanks for your help ^_^
Hi,
I haven’t done the code modification yet.
But I did a review of the published framework (DARwIn-OP_ROBOTIS_v1.6.0.zip), these are the findings I did:
From what I understood, the gyroscope and accelerometer are read in CM730.cpp in function CM730::BulkRead(), which is called from MotionManager::Process() in MotionManager.cpp.
The BulkRead() function dumps a large table of current data from the CM730 which contains the gyroscope and accelerometer updated data besides other stuff.
They are later used for example as:
MotionStatus::FB_GYRO = m_CM730->m_BulkReadData[CM730::ID_CM].ReadWord(CM730::P_GYRO_Y_L) – m_FBGyroCenter;
MotionStatus::RL_GYRO = m_CM730->m_BulkReadData[CM730::ID_CM].ReadWord(CM730::P_GYRO_X_L) – m_RLGyroCenter;
MotionStatus::RL_ACCEL = m_CM730->m_BulkReadData[CM730::ID_CM].ReadWord(CM730::P_ACCEL_X_L);
MotionStatus::FB_ACCEL = m_CM730->m_BulkReadData[CM730::ID_CM].ReadWord(CM730::P_ACCEL_Y_L);
I remember these values can be calculated from the i2c gyroscope and accelerometer device by scaling and adding an offset, I read about the range used by CM730 but I don’t have the info at hand, it was in a CM730 specification document.
So I think the best is to replace CM730::BulkRead() so it simulates the CM730 board and returns the information in the same format.
I have tried modifying cm 730.cpp by adding a function to call the value of the gyro, when compile ‘/Linux/build’ no error, but when trying to compile ‘/Linux/project/demo’ will error appear like this
/tmp/ccxrGH79.o: In function `Sensor::Sensor()’:
libSensor.cpp:(.text+0x14): undefined reference to `wiringPiI2CSetup’
libSensor.cpp:(.text+0x24): undefined reference to `wiringPiSetup’
libSensor.cpp:(.text+0x68): undefined reference to `wiringPiI2CReadReg8′
libSensor.cpp:(.text+0x80): undefined reference to `wiringPiI2CWriteReg16′
/tmp/ccxrGH79.o: In function `Sensor::getGyroX()’:
libSensor.cpp:(.text+0xbc): undefined reference to `wiringPiI2CReadReg8′
/tmp/ccxrGH79.o: In function `Sensor::getGyroY()’:
libSensor.cpp:(.text+0xf0): undefined reference to `wiringPiI2CReadReg8′
/tmp/ccxrGH79.o: In function `Sensor::getGyroZ()’:
libSensor.cpp:(.text+0x124): undefined reference to `wiringPiI2CReadReg8′
/tmp/ccxrGH79.o: In function `Sensor::getAccelX()’:
libSensor.cpp:(.text+0x158): undefined reference to `wiringPiI2CReadReg8′
/tmp/ccxrGH79.o: In function `Sensor::getAccelY()’:
libSensor.cpp:(.text+0x18c): undefined reference to `wiringPiI2CReadReg8′
/tmp/ccxrGH79.o:libSensor.cpp:(.text+0x1c0): more undefined references to `wiringPiI2CReadReg8′ follow
i ‘m get confused hahaha
I see you are using the Wiring Pi library for Raspberry Pi. I haven’t use it.
The compilation is okay, but the final linking is missing the Wiring Pi library.
I think you need include the library in Linux/project/demo/Makefile, under the LFLAGS variable.
Under Linux/build you are only compiling to “.o” objects, but not linking into an executable application, that is why it works, no need to locate the compiled library yet.
i will try it! hahaha thanks
hi llongeri, i have succeeded use gyro and accelero in raspberry, by adding method in CM-730.cpp and modification CM-730.h, then i calling the value in MotionManager.cpp. but idont know the original values of gyro+accelero in darwin-op, can yau tell me about values of gyro and accelero from CM-730? thanks
Hi arif,
I found this document with the information:
https://sourceforge.net/projects/darwinop/files/Hardware/Electronics/Sub%20Controller/Datasheets/DARwIn-OP%20Subcontroller%20Control%20Table.pdf/download
In the last pages it specifies that gyro range (0-1023) expected is:
0 -> -1600dps (degrees per second)
512 -> 0dps
1023 -> 1600dps
and for the accelerometer range (0-1023):
0 -> -4g
512 -> 0g
1023 -> 4g