Topics from meeting (October 25th)
Attendees: Jason Holmes, Scott Stack, Kin Chin Chua, Chris Romanoff
Created a list of all things that need to be interfaced with the processor and what kind of interface each one needs:
Interfaces Needed For Processor
- 1)Motor Control - 4 total PWM channels for right motor and left motor plus 2 additional ones to control the turret rotation and barrel pitch. Whether or not a PWM is 100% necessary will need to be discussed with Hong Kong.
- 2)Wireless Module – 1 SPI/UART/I2C interface to send data and configure the wireless module which will in turn send the data over the internet. The chosen tranceiver can handle all of those interfaces - the one chosen will be based on the required throughput.
- 3)Camera choices:
- a)Wireless IP camera – (nothing required for processor)
- b)Integrated camera – 9 General purpose IO and one I2C interface. Most CMOS cameras have 8 bit parallel output for image data and can be intialized and configured through an I2C interface. So, the board needs 8 general purpose for parallel data input and one for data clock. I2C interface to configure camera.
- 4)Accelerometer – 3 A/D input (1 for each axis)
- 5)IR Proximity Sensors – max of 4 A/D converter inputs (one for each sensor)
- 6)Pushbutton to detect collision – max of 4 general purpose IO (one for each button)
- 7)Fire Cannon (optional) – 1 general purpose IO (output a digital 1, which may need driving to fire)
- 8)GPS – (optional) – 2 General purpose IO pins for UART.
Wireless Transceiver
Our choice of camera will impact what kind of bandwidth our wireless transceiver will need to handle . We determined that most image sensor cameras output too much data to be sent usefully over the internet (wireless transceiver can handle a max of 1 Mbit per second UART, but also has a 44MHz clock and SPI - so any reasonable data rate could be handled. A 640x480 color image from one of the cameras we looked at will produce about 16Mbits per second at 30 frames per second.) . We tried to figure out a way to either interface an IP camera to our website or reduce the amount of data coming from a camera. This will have to be done using MJPEG compression.
