User`s guide

3 - Hardware

In the previous chapter the decision to evaluate the Spectrum Digital eZdsp F2812 was made.

The obvious reasons for choosing the eZdsp is the price and versatile nature of the chip,

should one like to mass produce a product – the DSP-chip from Texas Instruments is available

at a cost that none of the alternatives can hope to rival.

Another reason for choosing this development board is that MATLAB/Simulink has specific

software tools for programming it. How well these will fill our needs will hopefully be

determined during the progression of this report.

Now, let’s take a look at the features and performance offered by the DSP:

TMS320F2812 by Texas Instruments

Generation: TMS320F281x Controllers

Clock speed: 150 MHz

Memory: 256 Kb (though expandable up to 1 Mb)

Pulse Width Modulation signals: 16-channels, space vector capability

Analog to Digital-Conversion: 16-channels, 12-bit resolution, 80 ns conversion time

Input/Output-pins: Up to 56

Signal levels: [0, 3.3] V, (0-3 V on ADC-pins)

The DSP is fitted to a development board, the eZdsp F2812 from Spectrum Digital, and is

encased in a metal frame together with an interface card constructed as part of the master

thesis mentioned earlier in chapter 2.1.3. The interface card emulates the signal levels of

DSpace – this is of minor importance to this thesis however, since it is the capabilities and

behaviour of the DSP that is of primary concern.

The DSP connects to the host computer via its standard parallel port using a JTAG-interface

(Joint Test Action Group, IEEE 1149.1). The F281x offers real-time JTAG, a feature that is

otherwise missing on other processors of the C2000-series. Real-time JTAG grants the user

the option to modify memory content and peripherals while the processor is still running.

Since we’ll be executing most of our programs through Simulink we won’t be taking

advantage of this feature.

The DSP boasts a total of 56 I/O-pins, most which can have multiple functions assigned by

using flags in registers. Each of the pins has the abilty to function as a standard I/O-pin, that

is, either reading or writing digital data. Some of them, however, can be assigned special

functions like Pulse Width Modulation and Analog to Digital Conversion.

The F2812 handles these special functions using a pair of event managers, EVA and EVB.

The two EVx are identical and offer a range of functions that are especially interesting for

motor control and similar applications since most of these functions concern the PWM-

module.