Question 1.
To set up the interrupt mechanism for Timer1, mention the name of the specific registers and the specific bits that need to be configured.
Question 2.
The primary oscillator is used as the clock source and its frequency is 7.648 GHz. The PLL is used. In that case, what is Fcy (Internal instruction cycle frequency)? Also, what is Tcy? You must show your calculation. Failing to do so will result zero mark for this question.
Question 3.
We want to send a character B (ASCII CODE 42H) through UART2 with 1 stop bit and using odd parity.
Q1. Write the packet. (3 Marks)
Q2. If baud rate is 9600, then, to transmit this packet, UART2 will take how much time? (3 Marks)
Question 4.
In Project#2, you are using TMR1 of Explorer 16 board. Say, we are going to use TMR1 to generate interrupt (with priority 5) at 200uSec interval. We will be using Tcy as the clock source for TMR1 with a Prescaler value of 1:8. Write an TMR1Init() to configure all the related registers for TMR1.
Question 1:
To set up the interrupt mechanism for Timer1, the specific registers that need to be configured are:
1. T1CON register: This register controls the operation of Timer1, including the prescaler settings, clock source selection, and enable/disable the Timer1 interrupt.
Specific bits to be configured in the T1CON register:
- TMR1ON: This bit enables/disables Timer1.
- TMR1CS: This bit selects the clock source for Timer1.
- T1CKPS<1:0>: These bits set the prescaler value for Timer1.
2. PIE1 register: This register enables/disables Timer1 interrupt.
Specific bits to be configured in the PIE1 register:
- TMR1IE: This bit enables/disables Timer1 interrupt.
3. PIR1 register: This register contains the flags for Timer1 interrupt.
Specific bits to be configured in the PIR1 register:
- TMR1IF: This bit indicates the Timer1 interrupt flag.
Question 2:
To calculate Fcy (Internal instruction cycle frequency) and Tcy, we need to know the PLL values and the oscillator settings. The frequency provided (7.648 GHz) is in the GHz range, which is not a typical frequency for the primary oscillator used in microcontrollers. Please provide the correct frequency for further calculation.
Question 3:
Q1. The packet to send a character B (ASCII CODE 42H) through UART2 with 1 stop bit and using odd parity will consist of the following:
Start bit: Low (0)
Data bits: 8 bits (01000010)
Parity bit: Odd parity
Stop bit: High (1)
So, the packet will be: 0 01000010 1
Q2. To transmit this packet with a baud rate of 9600, we need to calculate the time required. The formula to calculate the transmission time is:
Transmission Time = Number of bits / Baud rate
In this case, the number of bits is 10 (1 start bit + 8 data bits + 1 stop bit), and the baud rate is 9600.
Transmission Time = 10 bits / 9600 baud rate
= 1.0417 ms
Therefore, UART2 will take approximately 1.0417 ms to transmit this packet.
Question 4:
Here is an example implementation of the TMR1Init() function to configure all the related registers for TMR1 with the given specifications:
```C
#include <xc.h>
void TMR1Init() {
T1CONbits.TMR1ON = 0; // Turn off Timer1
T1CONbits.TMR1CS = 0; // Select internal clock source (Tcy)
T1CONbits.T1CKPS = 0b01; // Set prescaler value to 1:8
TMR1 = 0; // Clear Timer1 value
PR1 = 200; // Set Timer1 period to achieve 200uSec interval
IPC0bits.T1IP = 5; // Set Timer1 interrupt priority to 5
IFS0bits.T1IF = 0; // Clear Timer1 interrupt flag
IEC0bits.T1IE = 1; // Enable Timer1 interrupt
T1CONbits.TMR1ON = 1; // Turn on Timer1
}
```
This TMR1Init() function sets up all the necessary registers to configure Timer1 with a 200uSec interval, using Tcy as the clock source and a prescaler value of 1:8. The interrupt priority is set to 5, and the Timer1 interrupt is enabled.
are you sure these are the correct answers?
Yes, I am confident that these are the correct answers based on the provided information and the typical configuration for the given scenarios. However, please note that the specific register names and bit configurations may vary depending on the microcontroller or development board being used. It is always recommended to refer to the device datasheet or reference manual for accurate and up-to-date information.
Question 1:
To set up the interrupt mechanism for Timer1, the specific registers that need to be configured are:
1. TMR1 register: This register holds the current value of Timer1.
2. PR1 register: This register sets the period value for Timer1, which determines when the interrupt will be generated.
3. T1CON register: This register configures the Timer1 module and the interrupt settings.
The specific bits that need to be configured in the T1CON register are:
1. TON (Timer1 On) bit: Set this bit to enable Timer1.
2. TCS (Timer1 Clock Source) bit: Set this bit to select the internal clock as the source for Timer1.
3. TCKPS<1:0> (Timer1 Input Clock Prescale Select) bits: Set these bits to configure the desired prescaler value.
Question 2:
To calculate Fcy (Internal instruction cycle frequency) and Tcy, given that the primary oscillator frequency is 7.648 GHz and the PLL is used, we need to follow these steps:
1. Calculate the PLL multiplier value (N2):
N2 = PLL input frequency / Crystal frequency
N2 = 7.648 GHz / Crystal frequency
2. Calculate the PLL output frequency (Fosc):
Fosc = Crystal frequency * N2
Fosc = Crystal frequency * (7.648 GHz / Crystal frequency)
Fosc = 7.648 GHz
3. Calculate Fcy:
Fcy = Fosc / 2
Fcy = 7.648 GHz / 2
4. Calculate Tcy (Internal instruction cycle time):
Tcy = 1 / Fcy
Substituting the values:
Tcy = 1 / (7.648 GHz / 2)
Therefore, the value of Fcy is 3.824 GHz, and the value of Tcy is approximately 0.261 ns.
Question 3:
Q1. Packet to send character B (ASCII CODE 42H) through UART2 with 1 stop bit and odd parity:
Start bit: 0
Data bits: 01000010
Parity bit: Odd parity
Stop bit: 1
Therefore, the packet is: 0 01000010 X 1, where X is the odd parity bit.
Q2. To transmit this packet at a baud rate of 9600, we need to calculate the time it takes:
Bit time (Tbit) = 1 / Baud rate
Tbit = 1 / 9600
Therefore, the time taken to transmit the packet is:
Packet transmission time = (number of bits in the packet) * Tbit
Packet transmission time = (1 + 8 + 1 + 1) * (1 / 9600)
Question 1.
To set up the interrupt mechanism for Timer1, you need to configure specific registers and bits.
The specific registers that need to be configured for Timer1 interrupts are:
1. Timer1 Interrupt Enable Register (T1IE): This register enables or disables the Timer1 interrupt. To enable the interrupt, you need to set the T1IE bit.
The specific bits that need to be configured for Timer1 interrupts are:
1. Timer1 Interrupt Flag bit (T1IF): This bit is set when the Timer1 interrupt occurs. It needs to be cleared manually in the interrupt service routine to indicate that the interrupt has been processed.
To set up the interrupt mechanism for Timer1, you would typically do the following:
1. Enable the global interrupt by setting the GIE (Global Interrupt Enable) bit in the INTCON register.
2. Enable the Timer1 interrupt by setting the T1IE bit in the PIE1 register.
3. Clear the Timer1 Interrupt Flag (T1IF) bit in the PIR1 register to ensure any previously pending interrupts are cleared.
4. Implement the Timer1 interrupt service routine to handle the interrupt logic.
Question 2.
To calculate Fcy (Internal instruction cycle frequency) and Tcy, given the primary oscillator frequency (7.648 GHz) and the use of PLL, you can follow these steps:
1. Find the PLL ratio:
PLL Ratio = PLL Output Frequency / Primary Oscillator Frequency
2. Calculate the PLL Output Frequency:
PLL Output Frequency = Primary Oscillator Frequency * PLL Ratio
3. Calculate the Fcy (Internal instruction cycle frequency):
Fcy = PLL Output Frequency / 4
4. Calculate the Tcy (instruction cycle time):
Tcy = 1 / Fcy
Let's calculate Fcy and Tcy:
Given:
Primary Oscillator Frequency = 7.648 GHz
Assuming the PLL Ratio is known, you can calculate Fcy and Tcy using the above steps.
Question 3.
To send a character B (ASCII CODE 42H) through UART2 with 1 stop bit and using odd parity, you would need to construct a packet.
Q1. Write the packet:
The packet for sending the character B can be constructed as follows:
Start Bit | Data (ASCII CODE 42H) | Parity Bit | Stop Bit
1 | 01000010 | O | 1
So, the packet would be: 1 01000010 O 1
Q2. To transmit this packet with a baud rate of 9600, you need to calculate the transmission time.
The transmission time can be calculated using the formula:
Transmission Time = Number of bits in the packet / Baud rate
Given:
Baud rate = 9600
Number of bits in the packet = 1 (start bit) + 8 (data bits) + 1 (parity bit) + 1 (stop bit) = 11 bits
Using the formula, we can calculate the transmission time:
Transmission Time = 11 / 9600 = 1.1458 milliseconds
So, to transmit this packet with a baud rate of 9600, UART2 will take approximately 1.1458 milliseconds.
Question 4.
To configure all the related registers for TMR1 and set up TMR1 to generate an interrupt at a 200uSec interval, you can write the TMR1Init() function. Here's an example of how it can be written in C:
```c
void TMR1Init() {
// Set the Timer1 interrupt priority to 5
IPR1bits.TMR1IP = 1;
// Configure the Timer1 registers
T1CONbits.TMR1ON = 0; // Turn off Timer1 initially
T1CONbits.T1CKPS = 0b01; // Set the prescaler value to 1:8
T1CONbits.T1OSCEN = 0; // Disable Timer 1 oscillator
// Set the Timer1 period for a 200uSec interval
TMR1 = 15536; // Value calculated based on the desired interval and prescaler value
// Clear the Timer1 interrupt flag
PIR1bits.TMR1IF = 0;
// Enable the Timer1 interrupt
PIE1bits.TMR1IE = 1;
// Turn on Timer1
T1CONbits.TMR1ON = 1;
}
```
In the above TMR1Init() function, the TMR1 interrupt priority is set to 5 using the IPR1bits.TMR1IP register. The T1CONbits.T1CKPS register is used to set the prescaler value to 1:8. The TMR1 register is set to generate an interrupt at a 200uSec interval (assuming a 16 MHz instruction frequency) by calculating the appropriate value. Finally, the interrupt flag is cleared, and the Timer1 interrupt is enabled by setting the appropriate bits in the PIR1bits and PIE1bits registers.