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Keeping the Sheep Corralled An engineer, a physicist, and a mathematician are shown a pasture with a herd of sheep, and told to put them inside the smallest.

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Presentation on theme: "Keeping the Sheep Corralled An engineer, a physicist, and a mathematician are shown a pasture with a herd of sheep, and told to put them inside the smallest."— Presentation transcript:

1 Keeping the Sheep Corralled An engineer, a physicist, and a mathematician are shown a pasture with a herd of sheep, and told to put them inside the smallest possible amount of fence. The engineer is first. He herds the sheep into a circle and then puts the fence around them, declaring, "A circle will use the least fence for a given area, so this is the best solution. The physicist is next. She creates a circular fence of infinite radius around the sheep, and then draws the fence tight around the herd, declaring, "This will give the smallest circular fence around the herd.

2 Keeping the Sheep Corralled The mathematician is last. After giving the problem a little thought, he puts a small fence around himself and then declares, "I define myself to be on the outside!"

3 Liquid Crystal Display Embedded Systems Interfacing Laboratory Timing, timing, timing …

4 Overview Task 1 – Prelab Task 2 – initPMP & _10usDelay Task 3 – Instruction Sequence and initLCD Task 4 – Application initPMP initLCD cmdLCD putLCD main

5 LCD Interface 8-bit Data Bus 3-bit Control Bus

6 LCD Interface 8-bit Data Bus 3-bit Control Bus

7 LCD Controller (SK ) Tianma TM162JCWAG1 16 Cols x 2 Lines SK0032 PIC24FJ128 1 Hitachi HD44780U Compatible Controller/Driver

8 LCD Controller (S6A ) Lumex LCD-SO Cols x 2 Lines S6A0069 PIC24FJ128 1 Hitachi HD44780U Compatible Controller/Driver

9 Parallel Master Port (PMP) Configure PMCON PMMODE PMADDR PMAEN See Prelab for suggested bit patterns

10 Control Signal R/W – Read/Write Select Signal RS – Register Select 0 = Instruction Register on write and Busy Flag on read 1 = Data Register on read and write E – Enable Signal Check waveforms to make sure your values for WAITB, WAITM, and WAITE meet timing requirements of LCD

11 WAITB, WAITM, and WAITE If WAITM = 0b0000, then WAITB and WAITE have no affect Else WAITM 0b0000, then WAITB, WAITM, and WAITE have an affect WAITM x Tcy (WAITB+1) x Tcy (WAITE+1) x Tcy E Stable

12 Delays – Task 2 – MPLAB SIM msDelay – Already in Peripherals.H Change msDelay scale factor to 333L _10usDelay(unsigned char n){ unsigned char count; for(count=n*usSCALE;count>0;count--){ asm(nop);..... } }

13 Task 2 Hello world Via holes and LCD pins have different signal pin outs. MSO Explorer-16 Check PMP timing against data sheet

14 Instruction Sequence – Task 3

15 Instruction Execution Times Power-On Delay >30 ms (100 ms) Slow Instructions ( > 1.35 ms) Clear display Home cursor Fast Instructions (> 43 us) All other commands and data

16 Functions – Task 3 initLCD – Initialize LCD Main initPMP initLCD Endless loop with Nop( )

17 Warning On Task 4 Task 3 may have confused the LCD controller Turn off power to Explorer-16 board. Turn on power to Explorer-16 board Debugger | Connect Reset Run Reset LCD Controller

18 Functions – Task 4 putLCD – send character to LCD cmdLCD – send new command to LCD Main initPMP and initLCD Endless loop Send message to display using putLCD Home cursor or clear display using cmdLCD


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