Presentation is loading. Please wait.

Presentation is loading. Please wait.

EE 134 / EE 101 Spring, 2002 Lecture 19 Exam 2 Solutions.

Similar presentations


Presentation on theme: "EE 134 / EE 101 Spring, 2002 Lecture 19 Exam 2 Solutions."— Presentation transcript:

1 EE 134 / EE 101 Spring, 2002 Lecture 19 Exam 2 Solutions

2 Problem 1. Figure 9.16 in text: Input Handshake Timing Diagrams Peter Spasov Microcontroller Technology: The 68HC11, Fourth Edition Copyright ©2002 by Pearson Education, Inc. Upper Saddle River, New Jersey All rights reserved. We are using Interlocked mode. STRB active low. We are not using pulsed mode here.

3 Another view of Problem 1: FIGURE 9-19 Centronics Parallel Interface Timing Diagram Peter Spasov Microcontroller Technology: The 68HC11, Fourth Edition Copyright ©2002 by Pearson Education, Inc. Upper Saddle River, New Jersey All rights reserved. 68HC11 PORTC STRA STRB PORTCL is read Data is latched into PORTCL The Centronics standard is a good example of input handshaking, where the MCU is inside the printer. In this problem we do not have an ACK signal.

4 * EE101/EE134 Exam 2 (The following is just a sample Main program) Main LDX#REGBAS;set IX for indexed addressing of ports BSRInit_PortC New_Data BSRInput_Data BSRDisplay_Bit BRANew_Data ********************************************************* *Subroutine: Initialize Port C *The MCU receives parallel data from the peripheral *using interlocked handshaking. * HNDS = 1, all other bits = 0 *Calling register: IX = REGBAS *Return regiester: none, but ACCA changed Init_PortC BCLRDDRC,X $FF ; all inputs (It was OK to not include this) LDAA#$10 STAAPIOC,X RTS ********************************************************* *Subroutine: Wait for data in PORTCL *Calling register: IX = REGBAS *Return register: ACCA contains input data Input_Data BRCLRPIOC,X $80 Input_Data; wait for STAF=1 LDAAPORTCL,X; ACCA = data RTS

5 Problem 3: FIGURE 9-3 Seven-Segment LED Display Connections Peter Spasov Microcontroller Technology: The 68HC11, Fourth Edition Copyright ©2002 by Pearson Education, Inc. Upper Saddle River, New Jersey All rights reserved. This is the type of LED display specified in the problem. A low (zero) bit turns that segment on.

6 FIGURE 9-4 Seven-Segment Code Examples Peter Spasov Microcontroller Technology: The 68HC11, Fourth Edition Copyright ©2002 by Pearson Education, Inc. Upper Saddle River, New Jersey All rights reserved.

7 ********************************************************* *Subroutine: Display 0 if Z set, 1 if Z clear *Uses common-anode 7-segment LED display (0=on, 1=off) *Assume PB0 -> a, PB1 -> b,..., PB6 -> g, PB7 -> N.C. *Calling registers: IX = REGBAS, Z bit in CCR *Return register: none, but ACCA changed Display_Bit BNEOne; be sure Z isn't changed before test Zero LDAA#$40; or $C0 STAAPORTB,X RTS One LDAA#$79; or $F9 STAAPORTB,X RTS

8 Problem 4: FIGURE x 4 Matrix Keyboard (Telephone Format) Peter Spasov Microcontroller Technology: The 68HC11, Fourth Edition Copyright ©2002 by Pearson Education, Inc. Upper Saddle River, New Jersey All rights reserved.

9 Problem 4: FIGURE 9-10 Parallel I/O with Keyboard. Also connect PC7 high using a pull-up resistor. Peter Spasov Microcontroller Technology: The 68HC11, Fourth Edition Copyright ©2002 by Pearson Education, Inc. Upper Saddle River, New Jersey All rights reserved. With this layout we need to setup the Port C Data Direction Register, DDRC, with $0F.

10 Problem 5: a.Printers b.Instruments c.One microsecond (two clock cycles) d.IRQ e.0 f.$D6 g.$1007 h.0 (or no change) i.Read, receive, or load j.Data bus


Download ppt "EE 134 / EE 101 Spring, 2002 Lecture 19 Exam 2 Solutions."

Similar presentations


Ads by Google