The KK7P DSPx Digital Signal Processor Module

NOTE: The DSPx Module has limited availability. The present stock is exhausted and no further production is planned until late 2011 or early 2012. If you wish to purcahse a DSPx, please check back then. I do not maintain a contact list and will not be able to alert you of product availability.

The DSPx is a fully wired and tested Digital Signal Processing Module suitable for DSP development and learning, as well as embedding into your own projects.

It is fully compatible with the DSP-10 2-meter Software Defined Radio.

It is also very useful as a DSP development platform, especially when used with the KDSP10 Interface Board.

Processor

The DSPx module uses the Analog Devices ADSP-2185N Digital Signal Processor chip running with a 40 MHz applied clock for an instruction rate of 80 MIPs. Multifunction instructions stretch the claimed MIPS specs to 160.

Memory

The ADSP-2185N has 80k bytes of internal memory. This is organized as 16k-by-24 for program memory and 16k-by-16 for data memory. Applications typically run from this internal memory.

Units produced since late 2003 are equipped with a 4 Megabit/512k byte Flash memory, Silicon Storage Technology SST39VF040 or similar. The Flash memory includes a loader that is compatible with the ADSP-2181 EZ Kit Lite. There are also several banks of FIR filter coefficients pre-loaded into the Flash, compatible with the KDSP2 open-source application code. The "BDMA" interface is used to access these coefficients. See the KDSP2 source code for an example of how to use the BDMA interface to access these coefficients.

CODEC

The DSPx module analog I/O is based on the Texas Instruments TLV320AIC23 or TLV320AIC23B CODEC. This device provides dual 16-bit ADC and DAC that run at a sample rate of 24 kHz (48 kHz in Monitor Rev D.1) in the default monitor programmed in the DSPx Flash memory. The CODEC is specified for and capable of running at a 96 kHz sample rate. It may also be configured for 24-bit rather than 16-bit operation, although the synchronous serial port ("SPORT") on the DSP chip is not capable of greater than 16-bit width without some software tricks.

Service Note

Early DSPx units, shipped in the Spring and Summer of 2003, sometimes exhibit a popping sound in the audio, or other staccato noise effects. This is due to capacitor C3 (next to the PLCC-socketed Flash memory chip) allowing the 1.8V regulator (U2) to oscillate.

If C3 is marked "106" it may be susceptible to this problem. If it is marked "475" then it has a special, low-ESR capacitor installed and should not exhibit this symptom.

If you have a DSPx with a "106" capacitor at C3, please email me to arrange obtaining a replacement part, or to have it replaced on your board.

A suitable replacement part is AVX TPSA475K010R1400 ( Mouser 581- TPSA475K010R1400).

Other

The CODEC and DSP serial interfaces are not directly compatible, so a CPLD (Complex Programmable Logic Device) is included to mitigate this incompatibility. The device chosen, Xilinx XCR3032XL, has very low power consumption. The CPLD also provides a means to configure the CODEC via a "bit-banged" SPI port. Finally, it provides a pair of software-readable inputs that may be used by your programs.

Several digital I/O pins are available on the digital I/O connector of the DSPx. The DSP bus is not available, however. Further details are in the DSPx manual, provided in PDF format.

The DSPx module measures 1.8 x 2.0 inches (4.6 x 5.2 cm). Power consumption is typically 240 mW or less.

Please note that KK7P, LLC and Lyle Johnson reserve the right to change the product specifications without notice or obligation. This may be due to: parts shortages or substitutions; to improve the product; circumstances beyond our direct control; or for any other reason. We cannot guarantee that the DSPx will be suited to any particular project to which you may wish to apply it.

You may browse or download the complete DSPx manual, in PDF format.

You may also download the schematic of the DSPx module.

Here are the pin locations of the DSPx module for those of you who want to connect it up without the benefit of the KDSP10. The pinouts are described in the DSPx manual.