Developing a bicycle speed-o-meter A comparison between the Analog Devices ADSP-BF533 (Blackfin) and Motorola MC68332

General Project concept Blackfin Programmable Flag (PF) Input Magnetic Sensor Signal Motorola Parallel Interface Timer (PIT) Input High speed clock signal 4/8/2019 Motorola Blackfin Comparison Part 1 , Copyright M. Smith, ECE, University of Calgary, Canada

Main function concept ulong DetermineSpeed(ulong wheelDiameter, ulong clockFrequency) #define ulong unsigned long int; extern “C” ulong CountClockASM(const int); // Assembly code interface extern “C” ulong CalculateSpeedASM(ulong, ulong, ulong); extern “C” void SetupInterface(void); ulong DetermineSpeed(ulong wheelDiameter, ulong clockFrequency) { // Get to known position on magnetic sensor signal unsigned long discard_count; unsigned long count_high, count_low; SetupInterface( ); discard_count = CountClockASM(while_MagneticSensorHigh); discard_count = CountClockASM(while_MagneticSensorLow); count_high = CountClockASM(while_MagneticSensorHigh); count_low = CountClockASM(while_MagneticSensorLow); return CalculateSpeedASM(count_high + count_low, wheelDiameter, clockFrequency); } 4/8/2019 Motorola Blackfin Comparison Part 1 , Copyright M. Smith, ECE, University of Calgary, Canada

Required Assembly Language extern “C” ulong CountClockASM(const int); // Assembly code interface extern “C” void SetupInterface(void); extern “C” ulong CalculateSpeedASM(ulong, ulong, ulong); ulong CountClockASM(const int high_low) { ulong clock_count = 0; while (magnetic_sensor = = high_low) { // if signal is unchanged from start // Must count just one clock signal low-to-high transition while (clock_signal = = high) /* wait */; while (clock_signal = = low) /* wait */; // Changes on low-to-high edge clock_count++; } return clock_count; 4/8/2019 Motorola Blackfin Comparison Part 1 , Copyright M. Smith, ECE, University of Calgary, Canada

What we need to know How can you pass parameters between “C/C++” and assembly code functions? How can you return a parameter from assembly code functions? What registers are available on the processor? How do you set up the interface between the processor and the real world Many signals are coming into processor, how do you separate (mask off) the signals you want from those you don’t? What are the basic operations for accessing memory? What are the basic ALU operations for this processor? 4/8/2019 Motorola Blackfin Comparison Part 1 , Copyright M. Smith, ECE, University of Calgary, Canada

Some characteristics of the processor Motorola Blackfin Data Bus 16 bits 32 bits Instruction Bus This is the “data” bus 64-bits Can fetch “data” on one bus and “instructions” on another bus at the same time Address bus 24-bits Accessing “slow” external memory Has both “fast” internal memory and “slower” external memory 4/8/2019 Motorola Blackfin Comparison Part 1 , Copyright M. Smith, ECE, University of Calgary, Canada

Programming model MC68332 Blackfin Data Registers D0, D1 …. D7 R0, R1 …. R7 Address Registers A0, A1 …. A6 Pointer Registers P0, P1 … P5 Frame Buffer Use A4 or A6 FP Stack Pointer SP (A7) SP Special DSP I0-I3, B0-B3, M0-M3, L0-L3 4/8/2019 Motorola Blackfin Comparison Part 1 , Copyright M. Smith, ECE, University of Calgary, Canada

Syntax examples MC68332 Blackfin Register to Register Move reg1  reg 2 32 bit operations MOVE.L D2, D1 (4 cycles @ 8 MHz) R1 = R2; (1 cycle @ 500 MHz) Register to Register Move reg1  reg 2 16 bit operations MOVE.W D2, D1 R1.L = R2.L; and also R1.H = R2.L; Register to Register Move reg1  reg 2 8 bit operations MOVE.B D2, D1 MOVE.B D2, D1 EXT.B D1; (8 cycle @ 8 MHz) R1 = R2.B (X); (1 cycle @ 500 MHz) 4/8/2019 Motorola Blackfin Comparison Part 1 , Copyright M. Smith, ECE, University of Calgary, Canada

Syntax examples MC68332 Blackfin Register to Register ADD reg1  reg 2 + reg3 32 bit operations MOVE.L D2, D1 ADD.L D3, D1 (10 cycles @ 8 MHz) R1 = R2 + R3; (1 cycle @ 500 MHz) Register to Register Move reg1  reg 2 + reg3 16 bit operations MOVE.W D2, D1 ADD.W D3, D1 (8 cycles @ 8 MHz) R1.L = R2.L + R3.L (NS); (1 cycle @ 500 MHz) Also R1 = R2 +|- R3; Means R1.L = R2.L – R3.L; and R1.H = R2.H + R3.H; Register to Register Move reg1  reg 2 + reg3 8 bit operations MOVE.B D2, D1 ADD.B D3, D1 R1.L = R2.B (X); R0.L = R3.B (X); R1.L = R1.L + R0.L (NS); ( > 3 cycles @ 500 MHz) 4/8/2019 Motorola Blackfin Comparison Part 1 , Copyright M. Smith, ECE, University of Calgary, Canada

In class exercise Do what? 4/8/2019 Motorola Blackfin Comparison Part 1 , Copyright M. Smith, ECE, University of Calgary, Canada

32-bit Memory Move operations Motorola Blackfin Value at memory location 1 placed at memory location 2 MOVE.L #MEM1, A0 MOVE.L #MEM2, A1 MOVE.L (A0), (A1) 36 cycles @ 8 MHz P0.H = hi(MEM1); P0.L = lo(MEM1); P1.H = hi(MEM2); P1.L = lo(MEM2); R0 = [P0]; [P1] = R0; > 6 cycles Multiple moves MOVE.L (A0)+, (A1)+ P1.H = hi(MEM2); P1.L = lo(MEM2); R0 = [P0++]; [P1++] = R0; R0 = [P0++]; 4/8/2019 Motorola Blackfin Comparison Part 1 , Copyright M. Smith, ECE, University of Calgary, Canada

16-bit Memory Move operations Motorola Blackfin Value at memory location 1 placed at memory location 2 MOVE.L #MEM1, A0 MOVE.L #MEM2, A1 MOVE.W (A0), (A1) 36 cycles @ 8 MHz P0.H = hi(MEM1); P0.L = lo(MEM1); P1.H = hi(MEM2); P1.L = lo(MEM2); R0 =W [P0]; W[P1] = R0; > 6 cycles Multiple moves MOVE.W(A0)+, (A1)+ MOVE.W (A0)+, (A1)+ P1.H = hi(MEM2); P1.L = lo(MEM2); R0 = W[P0++] (X); W [P1++] = R0; R0 = W[P0++] (X); W[P1++] = R0; R0 =W [P0++] (X); 4/8/2019 Motorola Blackfin Comparison Part 1 , Copyright M. Smith, ECE, University of Calgary, Canada

Memory Move operations Motorola Blackfin Multiple moves of registers MOVEM.L D0-D3/A0-A5, -(SP) [- - SP] = (R7:5, P5:3); Combination of memory moves and ALU operations Can also do parallel read and write operations together with math operations Syntax looks like this R1 = R2 | | R3 = [I0++] | | [I1++] = R4; Not all operations can be made parallel 4/8/2019 Motorola Blackfin Comparison Part 1 , Copyright M. Smith, ECE, University of Calgary, Canada

In class exercise Do what 4/8/2019 Motorola Blackfin Comparison Part 1 , Copyright M. Smith, ECE, University of Calgary, Canada

If – then – else constructs Signed tests Motorola Blackfin Set the condition code register CMP.L D0, D1 CC = D1 == D0; CC = D1 < D0; CC = D1 <= D0; Conditional jump BEQ NEXT_INSTR (D1 == D0) BLT NEXT_INSTR (D1 < D0) BLE NEXT_INSTR (D1 <= D0) IF CC JUMP NEXT_INSTR BNE NEXT_INSTR (D1 <> D0) BGE NEXT_INSTR (D1 >= D0) BGT NEXT_INSTR (D1 > D0) IF !CC JUMP NEXT_INSTR 4/8/2019 Motorola Blackfin Comparison Part 1 , Copyright M. Smith, ECE, University of Calgary, Canada

If – then – else constructs Un-signed tests Motorola Blackfin Set the condition code register CMP.L D0, D1 CC = D1 == D0 (UI); CC = D1 < D0 (UI); CC = D1 <= D0 (UI); Conditional jump BEQ NEXT_INSTR (D1 == D0) BLO NEXT_INSTR (D1 < D0) BLS NEXT_INSTR (D1 <= D0) IF CC JUMP NEXT_INSTR BNE NEXT_INSTR (D1 <> D0) BHS NEXT_INSTR (D1 >= D0) BHI NEXT_INSTR (D1 > D0) IF !CC JUMP NEXT_INSTR 4/8/2019 Motorola Blackfin Comparison Part 1 , Copyright M. Smith, ECE, University of Calgary, Canada

Example if-then-else code C++ example Motorola Blackfin IF (A > B) C = D; ELSE C = E; Set A, B, C, D, E to registers D0, D1, .. D4 CMP.L D1, D0 BLE ELSE MOVE.L D3, D2 JMP END_IF ELSE: MOVE.L D4, D2 END_IF: Set A, B, C, D, E to registers R0, R1, .. R4 CC = R1 < R0; IF !CC JUMP ELSE; R2 = R3; JUMP END_IF; ELSE: R2 = R4; END_IF: CC = R1 < R0; IF CC R2 = R3; IF !CC R2 = R4; 4/8/2019 Motorola Blackfin Comparison Part 1 , Copyright M. Smith, ECE, University of Calgary, Canada

Example loop code -- software loop C++ example Motorola Blackfin sum = 0; for (loop = 0; loop < 6; loop++) sum = sum + loop; Set D0 = sum , D1 = loop MOVE.L #0, D0 MOVE.L #0, D1 LOOP: CMP.L #6, D1 BGE PAST_LOOP ADD.L D1, D0 ADD.L #1, D1 BRA LOOP PAST_LOOP: Set R0 = sum , R1 = loop R0 = 0; R1 = 0; R2 = 6; LOOP: CC = R2 <= R1; IF !CC JUMP PAST_LOOP; R0 = R0 + R1; R1 += 1; JUMP LOOP 4/8/2019 Motorola Blackfin Comparison Part 1 , Copyright M. Smith, ECE, University of Calgary, Canada

Example loop code -- Harware loop C++ example Motorola Blackfin sum = 0; for (loop = 0; loop < 6; loop++) sum = sum + loop; Set D0 = sum , D1 = loop MOVE.L #0, D0 MOVE.L #0, D1 LOOP: CMP.L #6, D1 BGE PAST_LOOP ADD.L D1, D0 ADD.L #1, D1 BRA LOOP PAST_LOOP: Set R0 = sum , R1 = loop R0 = 0; R1 = 0; P1 = 6; LSETUP(LSTART, LEND) LC1 = P1; LSTART: R0 = R0 + R1; LEND: R1 += 1; Has a capability of 2 hardware (high-speed, zero overhead) loop 4/8/2019 Motorola Blackfin Comparison Part 1 , Copyright M. Smith, ECE, University of Calgary, Canada

Hardware test – wait while magnetic signal is “high” Motorola Blackfin Magnetic Signal Bit 1 of PADR register of PI/T interface Bit 10 of FIO_FLAG_D register of PF interface while (mag_signal == HIGH) /* wait */ ; MASK EQU 0x1 MOVE.L #PITBASE, A0 WHILE: MOVE.B PADR(A0), D0 AND.B #MASK, D0 CMP.B #MASK, D0 BEQ WHILE #define MASK 0x400 P0.H = hi(FIO_FLAG_D); P0.L = lo(FIO_FLAG_D); R1 = MASK; R0 = W[P0] (Z); R0 = R0 & R1; CC = R0 == R1; IF CC JUMP WHILE (BP); 4/8/2019 Motorola Blackfin Comparison Part 1 , Copyright M. Smith, ECE, University of Calgary, Canada

Subroutine / Function calls Motorola Blackfin extern “C” int FooASM(int, int, int) C = FooASM(1,2,3) .IMPORT _FooASM FP EQU A6 LINK FP, -16 MOVE.L D4, 12(SP) MOVE.L #1, 0(SP) MOVE.L #2, 4(SP) MOVE.L #3, 8(SP) JSR _FooASM MOVE.L D0, D4 .. Other code MOVE.L 12(SP), D4 UNLINK RTS .extern _FooASM LINK 20; [SP + 16] = R4; R0 = 1; R1 = 2; R2 = 3; CALL _FooASM; R4 = R0; R4 = [SP + 16]; UNLINK; RTS; 4/8/2019 Motorola Blackfin Comparison Part 1 , Copyright M. Smith, ECE, University of Calgary, Canada

Code conventions for subroutines / functions Motorola -- SDS Blackfin -- VisualDSP Volatile registers D0, D1 A0, A1 R0, R1, R2, R3 P0, P1, P2 Non-volatile registers D2, D2, D4, D5, D6, D7 A2, A3, A4, A5, A6, A7 R4, R5, R6, R7 P3, P4, P5, FP, SP Subroutine return value is passed in D0 R0 Subroutine OUTPARS OUTPAR1  0(SP) OUTPAR2  4(SP) OUTPAR3  8(SP) OUTPAR4  12(SP) OUTPAR1  R0 OUTPAR2  R1 OUTPAR3  R2 4/8/2019 Motorola Blackfin Comparison Part 1 , Copyright M. Smith, ECE, University of Calgary, Canada

In class exercise Do what? 4/8/2019 Motorola Blackfin Comparison Part 1 , Copyright M. Smith, ECE, University of Calgary, Canada

Information taken from Analog Devices On-line Manuals with permission http://www.analog.com/processors/resources/technicalLibrary/manuals/ Information furnished by Analog Devices is believed to be accurate and reliable. However, Analog Devices assumes no responsibility for its use or for any infringement of any patent other rights of any third party which may result from its use. No license is granted by implication or otherwise under any patent or patent right of Analog Devices. Copyright  Analog Devices, Inc. All rights reserved. 4/8/2019 Motorola Blackfin Comparison Part 1 , Copyright M. Smith, ECE, University of Calgary, Canada