Team E Meeting Minutes

Friday, November 12, 1999

Dataforth, Tucson, Arizona

11:00am

In Attendance at 11:00am:

Scott Hancock, Vishal Golia, Greg Sitrick,, Donnie Yazzie, and Dataforth personnel.

I. Microprocessor Issues

• We will use two loops for iterative process for communication between the components.
• The MicroChip microprocessor we are using has two modes: microprocessor mode and microcontroller mode.
• Ports C and D are a 16-bit multiplexer databus.
• We can use an external mux to get more I/O lines.
• We can use all parallel communication with the components.
• We may have to use flip-flops or decoders.
• Some MUX recommendations are for a MOX series from Vantis
• MOX111 is a good one for state machines.
• We will need a programmer for this.
• Usually they come with a card that goes into a PC and the software comes with it.
• They’re usually about $500; Lee Payne will provide if we decide to use it.
• The microprocessor we are using has two UART’s for serial communication.
• Port E will be used for PC communication as well.
• Dataforth engineers will provide a specifications book on the microprocessor.

II. Noise Reduction

• We will use two separate ground planes.
• Connect digital to analog at one place only.
• Use an integrated ADC (Delta Sigma).
• Successive Approximate ADC’s are harder to use.
• DAC, ADC, and PGA should be placed as close as possible and use a common ground.
• Use a lower clock speed. A good one is 14.756 Mhz, or a multiple of that number. This will provide little error (2-3%) on baud rates.
• Ground of ADC may be one connection point between analog and digital.
• 2 ADC conversions in 10ms for 100 Hz bandwidth.
• Buy a back plane board with a copper back for the analog section and connect it to a separate vector board for the digital section.
• Decouple every IC with .1 uF capacitors.
• Decouple the power supplies as well.

III. Other Information

• A good demo board is the PICDEM-17.
• The processor has 16k words for programming and 900 bytes of RAM.
• There is a watchdog timer internally.
• The processor has brown out detection and sleep mode as well.
• Lee will provide and adapter for the programming.