EE 120 Microprocessor‐Based System Design Lab Section 6. Lab 10. Interfacing LCD with Microcontrolle

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EE 120 Microprocessor‐Based System Design Lab Section 6 Spring 2021

Date: 05/06/2021 Student Name: Hung Vuong Lab Instructor Name: Naures Wagokh Lab Report Due Date: 05/10/2021

INTRODUCTION: In this Lab, we will interface the 84x48 Nokia 5110 Liquid Crystal Display (LCD) to the MSP432 microcontroller by Serial Peripheral Interface (SPI). Also, we will design, write, test, and debug communication functions between them.

Moreover, this lab uses a handshake scheme (busy and wait) to handle serial communication between software executed on MSP432, which is a master device, and Nokia 5110 LCD, which is a slave device.

Figure 1: Busy‐Wait Scheme.

Figure 2: MSP432 Serial Communication Interface.

LAB PROCEDURE AND RESULTS: 1. Hardware set-up:

Figure 3: MSP432 and Nokia 5110 Interface -

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Pin P9.4 (STE), P9.5 (CLK) and P9.7 (SIMO) are configured for SPI mode.

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Pin P9.4 connected to SCE: 0 = enable LCD, 1 = disable LCD.

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Pin P9.5 connected to SCLK: Clock.

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Pin P9.7 connected to DN: Serial data bits (command or data for display).

Pin P9.3 and P9.6 are set as GPIO. •

Pin P9.3 connected to RST: 0 = reset, 1 = run.

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Pin P9.6 connected to DC: 0 = DN is command, 1 = DN is data for display.

2. Lab11_LCD project: a. lcdcommandwrite function in Nokia5110.c: This function sends an 8-bit command to the LCD screen.

Figure 4: Code for lcdcommandwrite Function. b. lcddatawrite function in Nokia5110.c: This function sends an 8‐bit display data to the LCD screen.

Figure 5: Code for lcddatawrite Function. c. Nokia5110_OutString function in Nokia5110.c: This function prints a string of characters from the ASCII table shown in the Nokia5110.c program to the LCD screen.

Figure 6: Code for Nokia5110_OutString Function.

d. Nokia5110_OutUDec function in Nokia5110.c: This function displays a 16‐bit unsigned number in right‐justified 5‐digit decimal format on the LCD screen.

Figure 7: Code for Nokia5110_OutUDec Function.

e. Nokia5110_OutSDec function in Nokia5110.c: This function displays a 16‐bit signed number in right‐justified 6‐digit decimal format on the LCD screen.

Figure 8: Code for Nokia5110_OutSDec Function.

3. Result:

Figure 9: Output on the LCD Screen of Nokia 5110

4. Lab Questions: a. Question 1: Name at least 3 registers used in SPI protocol and describe their significance (important sections/bits, etc.)

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Status Register (STATW): is UCBUSY flag that checks if SPI is busy (STATW=0) or free (STATW=1).

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Receive Buffer Register (RXBUF): is the buffer that we need to load the data for transmitting to LCD.

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Interrupt Flag Register (IFG): is UCTXIFG flag that checks if Buffer is full (IFG=0) or empty (IFG=1), so the data is sent completely all bits at once and will not overwrite any bits.

b. Question 2: Clearly explain what are DIN (or MOSI/SIMO), D/C (or DC) and SCE(CE) pins on Nokia 5110 LCD. -

DIN (or MOSI/SIMO) pin: input for data line. MOSI/SIMO transmits data from the master (giving output) to the slave (getting input).

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D/C (or DC) pin: Input to select either command/address or data input.

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SCE(CE) pin: The enable pin allows data to be clocked in. The signal is active LOW.

c. Question 3: What is the bit-band alias address of Port 6 Output Register, bit 1?

Show calculations.

The memory map address of P6.1 output is calculated as below, where the regular 8-bit access for P6OUT is at address 42004C43H. For bit-banding of bit 1 of P6OUT, n = 4C43H and b = 1. Thus, the bit-band alias address of P6.1 output is: 42000000H + 32*4C43H + 4*1 = 42000000H + 20H*4C43H + 04H = 42000000H + 98860H + 04H = 42098864H

CONCLUSION: After doing this lab, I have learned so many things. I have learned how to interface a Nokia

5110 LCD using busy-wait synchronization. Also, I have understood about busy-wait and known why busy-wait was used for this interface and not interrupts. Furthermore, I am very interested in doing this lab, and this lab is very important and helpful for my future career.

REFERENCE [1] Le, Thuy T. (2020), EE 120 Microprocessor‐Based System Design Lab.