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Feature Article



Issue #204 June 2007
Are You Up for 16 Bits?
A look at Microchip's Family of 16 -Bit Microcontrollers
by Jeff Bachiochi

Start | Microchip's 16-Bit Family |Eeny, Meeny, Miny, Moe | PIC24F | PIC24H | Need DSP? | dsPIC30/33 | Standard Features | Peripheral Pin Select | DSP | DMA | Jump-Start PCBs | SMPS for $750 | Think, Enter, Win | Sources & PDF

Function execution times
Function Cycle count equation Conditions Number of cycles Execution time at 40 MIPS
Complex FFT** — N = 64 3,739 93.4 µs
Complex FFT** — N = 128 8,485 212.1 µs
Complex FFT** — N = 256 19,055 476.4 µs
Block FIR 53 + N (4 + M)  N = 32, M = 32 1,205 30.1 µs
Block FIR lattice 41 + N (4 + 7 M) N = 32, M = 32 7,337 183.4 µs
Block IIR canonic 36 + N (8 + 7 S) N = 32, S = 4 1,188 29.7 µs
Block IIR lattice 46 + N (16 + 7 M) N = 32, M = 8 2,350 58.7 µs
Matrix add 20 + 3 (C × R) C = 8, R = 8 212 5.3 µs
Matrix transpose 16 + C (6 + 3 (R – 1)) C = 8, R = 8 232 5.8 µs
Vector dot product 17 + 3N N = 32 113 2.9 µ
Vector max 19 + 7 (N – 2) N = 32 229 5.7 µs
Vector multiply 17 + 4 N N = 32 145 3.6 µs
Vector power 16 + 2 N N = 32 80 2 µs
Proportional integral derivative (PID) 30 N = 1 30 0.75 µs
   
*C = #columns, N = # samples, M = #taps, S = #sections, R = #rows
**Complex FFT routine inherently prevents overflow
Table 2—This table will give you a feel for the execution times you can expect when using the DSP algorithm library. The PID function is the latest to be included in this free library.

 

 

 

 


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