For any reference or data value unless otherwise mentioned, Explorer 16 board will be used as default. Show all your work for evaluation.
a. Consider the following configuration codes. Based on the codes below, how PORTD has been configured. Also determine the status (ON/OFF) of the LEDs connected to PORTD as the diagram?
TRISD = 0xAA;
PORTD = 0xAA;
PORTDbits.RD0 = 1;
PORTDbits.RD6 = 1;
TRISD = 0xAA - This line of code sets the lower 8 bits of PORTD as inputs (TRISD = 0b10101010) and the upper 8 bits as outputs (TRISD = 0b00000000). This means that pins RD0, RD2, RD4, and RD6 are configured as output pins, and pins RD1, RD3, RD5, and RD7 are configured as input pins.
PORTD = 0xAA - This line of code sets the value of PORTD as 0xAA (PORTD = 0b10101010). This means that pins RD0, RD2, RD4, and RD6 are set to logic high (1), and pins RD1, RD3, RD5, and RD7 retain their previous values.
PORTDbits.RD0 = 1 - This line of code specifically sets pin RD0 of PORTD to logic high (1). Since RD0 is an output pin and it was already set to logic high by the previous line of code, this line does not change the status of the LED connected to RD0.
PORTDbits.RD6 = 1 - This line of code specifically sets pin RD6 of PORTD to logic high (1). Since RD6 is an output pin and it was already set to logic high by the previous line of code, this line does not change the status of the LED connected to RD6.
Based on the configuration and the values set, the LEDs connected to RD0 and RD6 will be ON.
To understand how PORTD has been configured and the status of the LEDs connected to PORTD, let's break down the provided code step-by-step.
1. TRISD = 0xAA;
The TRISD register is responsible for setting the direction of each of the pins in PORTD. By assigning 0xAA to TRISD, we need to convert this hexadecimal value to binary for a better understanding.
0xAA = 10101010 (binary representation)
Each bit in the binary representation corresponds to a pin in PORTD. A '1' bit means the corresponding pin is configured as an input, and a '0' bit means it's configured as an output. Therefore, the pin configuration for PORTD is as follows:
RD7: 1 (input)
RD6: 0 (output)
RD5: 1 (input)
RD4: 0 (output)
RD3: 1 (input)
RD2: 0 (output)
RD1: 1 (input)
RD0: 0 (output)
Based on the configuration, RD0, RD2, RD4, and RD6 are configured as output pins.
2. PORTD = 0xAA;
The PORTD register is responsible for writing values to each of the pins in PORTD. By assigning 0xAA to PORTD, we need to convert this hexadecimal value to binary for better understanding.
0xAA = 10101010 (binary representation)
Each bit in the binary representation corresponds to a pin in PORTD. A '1' bit means the corresponding pin is set to logical high (ON), and a '0' bit means it's set to logical low (OFF). Therefore, the status of the LEDs connected to PORTD is as follows:
RD7: OFF
RD6: ON
RD5: OFF
RD4: ON
RD3: OFF
RD2: ON
RD1: OFF
RD0: ON
Based on the configuration, the LEDs connected to RD0, RD2, RD4, and RD6 will be ON, while the rest of the LEDs will be OFF.
To determine how PORTD has been configured and the status of the LEDs connected to PORTD, we need to understand the configuration codes and their impact on the PORTD register.
The configuration codes provided are as follows:
TRISD = 0xAA;
PORTD = 0xAA;
PORTDbits.RD0 = 1;
PORTDbits.RD6 = 1;
1. TRISD = 0xAA:
The TRISD register is responsible for configuring the I/O direction of the pins of PORTD. The TRISD register uses a bit-wise mapping to control individual pins. In this case, 0xAA is written to the TRISD register, which is 10101010 in binary. Breaking it down, we have:
- RD0 (LSB) is set as an input (TRISD0 = 1).
- RD1 is set as an output (TRISD1 = 0).
- RD2 is set as an input (TRISD2 = 1).
- RD3 is set as an output (TRISD3 = 0).
- RD4 is set as an input (TRISD4 = 1).
- RD5 is set as an output (TRISD5 = 0).
- RD6 is set as an input (TRISD6 = 1).
- RD7 (MSB) is set as an output (TRISD7 = 0).
2. PORTD = 0xAA:
The PORTD register is responsible for storing the current values of the I/O pins of PORTD. Writing 0xAA to the PORTD register sets the individual bits corresponding to the pins in the register. Breaking it down, we have:
- RD0 (LSB) is set to ON (1), assuming RD0 represents an LED.
- RD1 is set to OFF (0), assuming RD1 represents an LED.
- RD2 is set to ON (1), assuming RD2 represents an LED.
- RD3 is set to OFF (0), assuming RD3 represents an LED.
- RD4 is set to ON (1), assuming RD4 represents an LED.
- RD5 is set to OFF (0), assuming RD5 represents an LED.
- RD6 is set to ON (1), assuming RD6 represents an LED.
- RD7 (MSB) is set to OFF (0), assuming RD7 represents an LED.
3. PORTDbits.RD0 = 1:
Here, we explicitly set the RD0 pin to ON (1), overriding the previous configuration.
4. PORTDbits.RD6 = 1:
Similarly, we explicitly set the RD6 pin to ON (1), overriding the previous configuration.
Based on the above information, the configuration of PORTD is as follows:
- RD0 is set as an output and is ON.
- RD1 is set as an output and is OFF.
- RD2 is set as an input.
- RD3 is set as an output and is OFF.
- RD4 is set as an input.
- RD5 is set as an output and is OFF.
- RD6 is set as an output and is ON.
- RD7 is set as an output and is OFF.
Assuming the LEDs are connected to the output pins, the status of the LEDs connected to PORTD would be:
- RD0 LED: ON
- RD1 LED: OFF
- RD2 LED: N/A (input pin)
- RD3 LED: OFF
- RD4 LED: N/A (input pin)
- RD5 LED: OFF
- RD6 LED: ON
- RD7 LED: OFF
Please note that the information provided assumes the default configuration of the Explorer 16 board unless otherwise mentioned.