Education Library

Let's Talk DSP

Algorithms: A defined procedure for solving a problem or performing an operation. Algorithms are stored in a DSP through a series of instructions.

Analog: Analog refers to electrical signals that vary continuously over time. Analog signals must be converted into digital form by an analog to digital converter in order for a DSP to process them.

Bits: The smallest unit that a digital word can be broken down to. The number of bits reflects the word width. The greater the number of bits in a word, the larger the number that can be represented by that word.

Cycle Time: Length of time to complete an instruction.

Digital: Digital describes electronic technology that generates, stores, and processes data in terms of two states: positive and non-positive. Positive is represnted by the number 1 and non-positive by the number 0. Data transmitted or stored with digital technology is expressed as a string of 0's and 1's. Each of these state digits is referred to as a bit.

DMA (Direct Memory Accessing): The DSP's I/O processor supports DMA of data between DSP memory and external memory, host or peripherals through the external, host, serial, SPI, and UART ports. Each DMA operation transfers an entire block of data.

Fixed Point: A method used by the DSP to manipulate and represent numbers best suited not to grow larger than the biggest number that can be held in a single internal register. The size of the register is determined by the number of bits it can contain. E.g., 32-bit numbers can be larger than 16-bit numbers.

Floating Point: A system where a number is represented with a mantissa and an exponent. E.g., a x 2b where "a" is the mantissa and b is the exponent. This method allows the DSP to manipulate very small numbers or very large numbers. Floating Point processors represent numbers in a standard format established by the IEEE. It is a scientific notation represented by 32-bits.

Harvard Architecture: DSPs use memory architectures that have separate buses for program and data storage. The two buses let the DSP get a data word and an instruction simultaneously.

I/O: Input/Output. Interfaces/devices used for transferring data and control information between the DSP and peripherals.

I/O Processor: The DSP has a distributed DMA architecture with DMA controllers for each DMA capable peripheral. Also, most ports have some direct (non-DMA) access to internal memory and I/O memory. The term I/O processor refers globally to the DMA controllers, DMA channel arbitration, and peripheral-to-bus connections.

MIPS: Millions of Instructions Per Second where each instruction can perform multiple operations.

MACS: Multiply-and-Accumulate Per Second

MOPS: Million of Operations Per Second

MFLOPS: Million of Floating Point Operations Per Second

Von Neumann Architecture: This is the architecture used by most (non-DSP) microprocessors. This architecture uses a single address and data bus for memory access.

Word: A string of bits representing a data value. Word lengths in DSPs are typically 16-bit, 24-bit, 32-bit, and 48-bit.