MiMu BLOG

Last Preparation Before Berlin

The sparkfun order arrived today so Tom, Kelly and I spent some time finishing of Glover and preparing the parts for the workshop.

One of the two previous FTDI cables I ordered from sparkfun didn’t work so I tested each of the ten new cables with teh ArduIMU. The FTDI cable connects to the ArduIMU with the metal connectors facing down and the black wire in teh centre.

The host machine settings for the FTDI device must be changed to “Set RTS On Close”. This is because the ArduIMU uses its CTS input to reset the ArduIMU for when bootloading. The FTDI default settings also include a Latency timer of 16 ms.  This should be reduced to 1 ms to minimise latency.  This is done through device manager if using Windows.

I had to calibrate the ArduIMU that was permanently fixed to the glove. This was tricky and needed to whole glove to be secured to the calibration cube while ensuring the ArduIMU board itself remains aligned to the calibration cube.

In a previous post I changed the RN-42 (Bluetooth module) settings to disabled remote config. Tom found that the new Bluetooth modules (still with factory default settings) were unreliable and would disconnect unexpectedly. I changed the settings as described in the previous post for all the Bluetooth modules.

To calibrated the ten new ArduIMUs, each had to be fitted to the calibrated cube, powered and connected to a Bluetooth module to communicate with the PC calibration software.  To achieve this, I glued a Bluetooth module to the calibration cube with a JST battery connector soldered to its VCC and GND pins.  This would provide power and data through a single connector as well as align the ArduIMU to the calibration cube.  Some ArduIMUs would sit at an angle so I used masking tape to hold them flat.  This is not ideal as the thin (0.8mm) PCB could be stressed and cause the gyroscope bias to shift.