1. 1 Bringing it all together: Exploring the EVB Today: First Hour: Bringing it all together by exploring the EVB –Section 4.1 - 4.7.2 of Huang’s Textbook –In-class Activity #1 Second Hour: Answers to your questions

2. 2 Internal Bus #1 M A R Memory Address Bus M B R Internal Bus #2 Data Bus Register File (A, B, IX, IY, IR) MUX CCRCCR P C Recap: M6811 Datapath ALU A 16 - A 0 D 7 - D 0 The datapath unit consists of registers, buses connecting them, and the ALU

3. 3 Internal Bus #1 M A R Memory Address Bus M B R Internal Bus #2 Data Bus Register File (A, B, IX, IY, IR) MUX CCRCCR P C Recap: M6811 Control Unit ALU A 16 - A 0 D 7 - D 0 Control Unit

4. 4 E R/W AS AD7 - AD0 68HC11 PC7- PC0 A15 - A8 PB7- PB0 MODB MODA Bus Recap: Time-Multiplexed Bus 1 1 Other pins not shown

5. 5 E R/W A15-A8 AD7-AD0LO-ADDRDATA AS XTAL Recap: Bus Timing Diagram HI ADDR Magic Moment #1 Magic Moment #2

6. 6 Recap: De-multiplexing the Address E R/W AS AD7-AD0 68HC11 PC7-PC0 A15-A8 PB7-PB0 MODB MODA Bus 1 1 Other pins not shown D0-D7 Q0-Q7 A0-A7 LS 373 LE Address A0-A7 latched on the falling edge of AS OE 0 Magic Moment #1

7. 7 Bus Interfacing Summary Step 1: Bus Demultiplexing –Use address strobe (AS) and a latch to Demultiplex the address and data lines Step 2: Address Decoding –Use Boolean logic to decode the desired address Chip Select = Compare(A 15 … A 0 = desired address ) AND (E = 1) Step 3: Generate Read/write control signal – Use the second half of E cycle to generate Read/Write signal for RAM chip

8. 8 Recap: Memory Interfacing A2 A1 A0 E3 E2E1 A15 A14 A13 E R/W A12 – A8 AS AD7-AD0 LE D7-D0 O7-O0 OE I/O8 - I/O1 WE CS1 CS2 V DD O2 A12-A0 OE 8K RAM Decoder 68HC11 Latch 74LS00 74LS04 $4000 - $5FFF

9. 9 Recap: Memory-mapped I/O Every I/O device “appears” to the CPU as a memory location –Use LDAA and STAA for input/output Several useful I/O devices, and some memory devices are already interfaced for us on the 6811 chip.

10. 10 Event counter Generate periodic interrupts Periodically check the chip Put code in ROM Put non- volatile data in EEPROM SPI for inter- connecting 6811’s SCI for connecting to host computer Input analog signals Fancy general- purpose timer Bus for expansion

11. 11 Port Replacement Unit (PRU) Recovers PORTB and PORTC in expanded mode E R/W AS AD7-AD0 68HC11 PC7-PC0 A15-A8 PB7-PB0 MODB MODA 1 1 Other pins not shown PORTB PORTC Port Replacement Unit (PRU) STRA STRB

12. 12 Building The EVB 6811 Latch PRU 8K ROM 8K RAM Port A PD0 - 5 Port E Port B Port C AD0 - AD7 A0 - A7 A8 – A15 A0 – A15 AD0 - AD7

13. 13 Adding Communication ACIA 6811 Latch PRU 8K ROM 8K RAM Terminal (P2) Host Computer (P3) RS-232 Drivers & Receivers Port A PD0 - 5 Port E Port B Port C AD0 - AD7 A0 - A7 A8 – A15 A0 – A15 AD0 - AD7 PD1 PD0 TX RX Control RX TX Control RX TX

14. 14 Software Picture of EVB Memory Map –Specifies what addresses are for what BUFFALO Utility Routines –Useful for development & debugging BUFFALO command interpreter Interrupt vector jump table in RAM

15. 15 Do Activity #1 Now Due: End of Class Today. RETAIN THE LAST PAGE(S) (#3 onwards)!! During studio time this week: Catch up with experiments. Summarize reading of Chapter 4, Chapter 5 (sections 5.1-5.4), and Chapter 6 (6.1 – 6.7) That’s it. No more new material!