The reference voltage for a 12-bit DAC is 3.0V. Determine DAC output voltage if the specified
digital code is converted and the DAC is used in 12-bit right-aligned mode. Show your work.
Digital Code: 0X07FF
To determine the DAC output voltage, we need to convert the digital code to an equivalent voltage.
Given:
Reference voltage (Vref) = 3.0V
Digital Code = 0X07FF
In a 12-bit right-aligned mode, the digital code provided represents the maximum value that can be achieved, which is 2^12 - 1 = 4095.
To convert the digital code to voltage, we can use the following formula:
DAC output voltage = (Digital Code / (2^N - 1)) * Vref
where N is the number of bits, i.e., in this case, N = 12.
Plugging in the values, we get:
DAC output voltage = (0X07FF / (2^12 - 1)) * 3.0V
Now, let's calculate the output voltage:
DAC output voltage = (2047 / 4095) * 3.0V
= (0.499) * 3.0V
= 1.497V
Therefore, the DAC output voltage for the specified digital code (0X07FF) in a 12-bit right-aligned mode is 1.497V.
2. The reference voltage for a 12-bit DAC used in 12-bit right-aligned mode is 3.0V. Determine the
value of the DAC data output register (DOR) to obtain the specified output voltage. Show your
work. Voltage: 0.38V
To determine the value of the DAC data output register (DOR) that will produce the specified output voltage, we can rearrange the formula for the DAC output voltage:
DAC output voltage = (DOR / (2^N - 1)) * Vref
Given:
Reference voltage (Vref) = 3.0V
Desired output voltage = 0.38V
Rearranging the formula, we have:
DOR = (Desired output voltage / Vref) * (2^N - 1)
Plugging in the values:
DOR = (0.38V / 3.0V) * (2^12 - 1)
Now, let's calculate the value of DOR:
DOR = (0.1267) * (4095)
= 519.18
Since the DAC data output register (DOR) is usually an integer value, we round 519.18 to the nearest whole number.
Therefore, the value of the DAC data output register (DOR) that will produce a specified output voltage of 0.38V in a 12-bit right-aligned mode with a reference voltage of 3.0V is 519.
3. Enable channel 2 of the microcontroller DAC. Write a program to convert the specified digital
code using 12-bit right-aligned mode. Measure DAC output voltage with DMM.
Demonstrate your program to instructor. Dac Code: 0x11AF
To enable channel 2 of the microcontroller DAC and convert the specified digital code in 12-bit right-aligned mode, you would need to write a program in the programming language used for your microcontroller.
Here is an example of a program in C language that accomplishes this task:
```c
#include <stdio.h>
#include <stdint.h>
#include <stdbool.h>
// DAC channel registers
volatile uint32_t *DAC_CTRL = (uint32_t*)0xaddress_of_DAC_CTRL_register;
volatile uint32_t *DAC_DATA = (uint32_t*)0xaddress_of_DAC_DATA_register;
// Function to enable DAC channel 2
void enable_DAC_channel2() {
// Set the channel 2 enable bit in the DAC control register
*DAC_CTRL |= (1 << 1);
}
// Function to convert and output digital code in 12-bit right-aligned mode
void convert_DAC(uint16_t digital_code) {
// Right-align the digital code
digital_code = digital_code << 4;
// Write the digital code to the DAC data register
*DAC_DATA = digital_code;
}
int main() {
// Enable DAC channel 2
enable_DAC_channel2();
// Specify the digital code (in hex, 0x11AF)
uint16_t digital_code = 0x11AF;
// Convert and output the digital code using the DAC
convert_DAC(digital_code);
// Measure the DAC output voltage using a digital multimeter (DMM)
// Connect the DMM to the output pin of the DAC channel 2
return 0;
}
```
Please note that the addresses used for the DAC control and data registers are placeholders and should be replaced with the appropriate addresses for your specific microcontroller.
After writing the program, you can compile and upload it to your microcontroller. Make sure to connect the output pin of channel 2 of the DAC to the input of your digital multimeter (DMM) and set the DMM to measure voltage. Execute the program and the DMM should display the measured DAC output voltage.
Remember to consult your microcontroller's documentation for specific details on DAC configuration and programming.
4. Modify your program to convert the same digital code as in question 2 but in 12-bit left-aligned
mode. Measure DAC output voltage with DMM.
If the voltage is different from the result observed in question 3, explain why
To modify the program to convert the digital code in 12-bit left-aligned mode, you would need to update the `convert_DAC` function. Here's an example of how the program could be modified:
```c
#include <stdio.h>
#include <stdint.h>
#include <stdbool.h>
// DAC channel registers
volatile uint32_t *DAC_CTRL = (uint32_t*)0xaddress_of_DAC_CTRL_register;
volatile uint32_t *DAC_DATA = (uint32_t*)0xaddress_of_DAC_DATA_register;
// Function to enable DAC channel 2
void enable_DAC_channel2() {
// Set the channel 2 enable bit in the DAC control register
*DAC_CTRL |= (1 << 1);
}
// Function to convert and output digital code in 12-bit left-aligned mode
void convert_DAC(uint16_t digital_code) {
// Left-align the digital code
digital_code = digital_code << 4;
// Write the digital code to the DAC data register
*DAC_DATA = digital_code;
}
int main() {
// Enable DAC channel 2
enable_DAC_channel2();
// Specify the digital code (in hex, 0x11AF)
uint16_t digital_code = 0x11AF;
// Convert and output the digital code using the DAC in left-aligned mode
convert_DAC(digital_code);
// Measure the DAC output voltage using a digital multimeter (DMM)
// Connect the DMM to the output pin of the DAC channel 2
return 0;
}
```
After modifying and executing the program, measure the DAC output voltage using the digital multimeter (DMM) connected to the output pin of channel 2 of the DAC.
The observed voltage may be different from the result observed in question 3 for two reasons:
1. Alignment: In left-aligned mode, the most significant bits of the digital code are used to generate the output voltage. This means that the effective range of the DAC is reduced. In right-aligned mode, the least significant bits are used, resulting in a higher precision.
2. Quantization: The DAC's resolution determines the number of possible output voltage levels. In this case, a 12-bit DAC has 2^12 (4096) possible levels. When converting a digital code to voltage, each level represents a step. In left-aligned mode, the voltage steps may be further apart compared to right-aligned mode, leading to a different voltage output.
Therefore, it's expected that the voltage measured in question 4 (left-aligned mode) may be different from the voltage observed in question 3 (right-aligned mode).
5. Modify your program to convert the same digital code as in question 3 but in 8-bit right-aligned
mode. If the voltage is different from the result observed in question 3 explain why
To modify the program to convert the digital code in 8-bit right-aligned mode, you would need to update the `convert_DAC` function. Here's an example of how the program could be modified:
```c
#include <stdio.h>
#include <stdint.h>
#include <stdbool.h>
// DAC channel registers
volatile uint32_t *DAC_CTRL = (uint32_t*)0xaddress_of_DAC_CTRL_register;
volatile uint32_t *DAC_DATA = (uint32_t*)0xaddress_of_DAC_DATA_register;
// Function to enable DAC channel 2
void enable_DAC_channel2() {
// Set the channel 2 enable bit in the DAC control register
*DAC_CTRL |= (1 << 1);
}
// Function to convert and output digital code in 8-bit right-aligned mode
void convert_DAC(uint8_t digital_code) {
// Write the digital code to the DAC data register
*DAC_DATA = digital_code;
}
int main() {
// Enable DAC channel 2
enable_DAC_channel2();
// Specify the digital code (in hex, 0x11AF)
uint8_t digital_code = 0xAF; // Take the least significant 8 bits of the original 12-bit code
// Convert and output the digital code using the DAC in 8-bit right-aligned mode
convert_DAC(digital_code);
// Measure the DAC output voltage using a digital multimeter (DMM)
// Connect the DMM to the output pin of the DAC channel 2
return 0;
}
```
After modifying and executing the program, measure the DAC output voltage using the digital multimeter (DMM) connected to the output pin of channel 2 of the DAC.
The observed voltage may be different from the result observed in question 3 for two reasons:
1. Resolution: In 8-bit mode, the DAC has fewer bits available to represent the digital code, resulting in a lower resolution compared to a 12-bit DAC. This means there will be fewer possible voltage output levels, and the voltage steps will be larger.
2. Reference voltage: The program assumes the same reference voltage as mentioned in question 3 (3.0V). If the reference voltage is different in reality, it would result in a different DAC output voltage.
Therefore, it's expected that the voltage measured in question 5 (8-bit right-aligned mode) may be different from the voltage observed in question 3 (12-bit right-aligned mode) due to both the reduced resolution and the possibility of a different reference voltage being used.