The MSP430xxxx

1. ECE 2560 The MSP430xxxx Department of Electrical and Computer Engineering The Ohio State University ECE 3561 - Lecture 1

2. Today • The MSP430 Microcontroller • What is a microcontroller • The Physical Chip/Processor • Memory structure • Addressing Modes ECE 3561 - Lecture 1

3. The MSP430 Microcontroller • What is a microcontroller? • A microprocessor with memory and I/O port support directly on chip. It also includes controllers for interfaces such a JTAG, SPIO, A-to-D conversion on board. • With the support on chip, microcontrollers are very important in design and implementation of embedded systems. ECE 3561 - Lecture 1

4. The MSP430 • A von-Neumann style architecture • Key features • Ultralow-power architecture • 0.1 uA RAM rentention • 0.8 uA real-time clock mode • 250 uA/MIPS active • High-performance A-to-D conversion • 12-bit or 10-bit ADC, 12-bit dual-DAC • 200 ksps • 16-bit RISC processor features • Large Register file • Compact code design • 27 core instructions • 7 addressing modes ECE 3561 - Lecture 1

5. The MSP430 • Block Diagram of internal structure – high level ECE 3561 - Lecture 1

6. MSP430 • Memory structure – logical • 16-bit addressable • 64K bytes (64KB) • Amount of Flash/ROM and RAM vary by device • Last 16 words of Flash/ROM used for the Interrupt Vector Table • I/O is memory mapped ECE 3561 - Lecture 1

7. Memory data organization • Bytes can be at even or odd addresses • Words are only at even addresses • The low byte of a word is at the even address. • The high byte of a word is at the odd address ECE 3561 - Lecture 1

8. Memory dump • Big endian and little endian • (the 430) • Little endian is more logical but… (pg 27 of text) • If memory is dumped by the debugger • Addresses increase from low to high across a line • Display is low-order-byte high-order-byte • so $1234 is displayed $34 $12 • bytes look reversed but consistent with • their address • Can be avoided by getting the dump in words versus bytes. (Will see this later in examples) (Code composer supports this) ECE 3561 - Lecture 1

9. The MSP430 CPU • Incorporates features to support modern programming techniques (Don’t need go to’s) • The features • Calculated branching • Table processing • 27 RISC instructions • 7 addressing modes • All instructions use all the addressing modes • Full register access • Single cycle register operations (RISC) • Direct memory-to-memory transfers • Constant generator provides most used values ECE 3561 - Lecture 1

10. The MSP430 data path • There are 16 registers • Contents are 16-bits • User has access to all registers • 4 registers are special purpose • Note bus structure • MDB – Memory Data Bus • MAB – Memory Address Bus • Also have 2 internal bussed to deliver 2 operand to ALU • Diagram is called the datapath of the processor • See Users Guide ECE 3561 - Lecture 1

11. General purpose registers • R4 thru R15 • Registers are indistinguishable • Can be used as • Data Registers • Address Registers • Index values • Can be accessed with byte or word instructions • There is Register-Byte operation and Byte-Register operation – covered later ECE 3561 - Lecture 1

12. Addressing Modes • MSP430 addressing modes • Addressing mode – the way in which the operand(s) of an instruction are accessed, i.e., the effective addresses are calculated. • 7 modes supported • Register Mode – (Rn) – operands are in registers • Immediate Mode – #N – The operand is part of the instruction • Instructions have format OPCODE #OPERAND • Absolute Mode – &ADDR – The address of the operand is given by the word following the opcode • Instructions have format OPCODE &ADDRESS ECE 3561 - Lecture 1

13. Addressing Modes (2) • Remainder of addressing mode • Indexed Mode – X(Rn) – (Rn+X) points to (is the address of) the operand. The value X is the next word in the instruction stream after the OPCODE. • Symbolic Mode – ADDR – (PC+X) points to the operand. X is the next word. • Indirect Register Mode - @Rn – Rn is used as a pointer to the operand. • Indirect Autoincrement - @Rn+ - Rn is used as a pointer to the operand. After access Rn is incremented by 1 for .B instructions and by 2 for .W instructions ECE 3561 - Lecture 1

14. Register Mode Addressing • Note gives action if only a byte • Form is • MOV.B R1,R2 ECE 3561 - Lecture 1

15. Immediate Mode addressing • Operand is part of instruction • Destination can be a register or a memory location. • If a register instruction is only 2 words ECE 3561 - Lecture 1

16. Absolute Mode Addressing • One of operands can be a register ECE 3561 - Lecture 1

17. Absolute Mode Addressing (2) • Effect ECE 3561 - Lecture 1

18. Indexed Mode Addressing • Summary ECE 3561 - Lecture 1

19. Indexed Mode Addressing (2) • Action ECE 3561 - Lecture 1

20. Symbolic Mode Addressing • Summary ECE 3561 - Lecture 1

21. Symbolic Mode Addressing (2) • Action ECE 3561 - Lecture 1

22. Indirect Register Mode • Summary ECE 3561 - Lecture 1

23. Indirect Register Mode (2) • Action ECE 3561 - Lecture 1

24. Indirect Autoincrement Mode • Summary ECE 3561 - Lecture 1

25. Indirect Autoincrement Mode (2) • Action ECE 3561 - Lecture 1

26. Assignment • The MSP 430 Users Guide has been added to the course webpage. • The information of this lecture can be found there (section 3.3). • Quiz next week – (again) • Some 430 questions ECE 3561 - Lecture 1