1. The clock signal for timer TIM6 is 80 MHz. Determine the values of timer prescaler (TIM6_PSC)
and autoreload (TIM6_ARR) registers to get the specified timer overflow period (Toverflow). Show
your work.
Toverflow = 4 ms
To calculate the values of the timer prescaler (TIM6_PSC) and autoreload (TIM6_ARR) registers, we need to use the following formula:
Toverflow = (TIM6_ARR + 1) * (TIM6_PSC + 1) / Fclock
where Fclock is the frequency of the clock signal (80 MHz in this case).
Given Toverflow = 4 ms and Fclock = 80 MHz, we can rearrange the formula to solve for TIM6_ARR and TIM6_PSC:
TIM6_ARR + 1 = Toverflow * Fclock / (TIM6_PSC + 1)
Substituting the given values:
TIM6_ARR + 1 = 4 ms * 80 MHz / (TIM6_PSC + 1)
Simplifying:
TIM6_ARR + 1 = 320 * (10^6) / (TIM6_PSC + 1)
To find the values of TIM6_ARR and TIM6_PSC, we need to iterate through all possible combinations until we find the one that satisfies the equation. Here is one possible combination:
TIM6_PSC = 99
TIM6_ARR = 320 - 1 = 319
Let's check if this combination gives us the desired Toverflow:
Toverflow = (319 + 1) * (99 + 1) / 80 MHz
= 320 * 100 / 80 MHz
= 4000 us
= 4 ms
So, the values of the timer prescaler (TIM6_PSC) and autoreload (TIM6_ARR) registers to achieve a timer overflow period of 4 ms are:
TIM6_PSC = 99
TIM6_ARR = 319
where did you get 10^6?
I apologize for the error. The correct value to use is 1000000, not 10^6. Let me recalculate the values using the correct value.
TIM6_ARR + 1 = Toverflow * Fclock / (TIM6_PSC + 1)
TIM6_ARR + 1 = 4 ms * 80 MHz / (TIM6_PSC + 1)
TIM6_ARR + 1 = 4 ms * 80 * 10^6 Hz / (TIM6_PSC + 1)
TIM6_ARR + 1 = 4 * 80 * 10^6 * 10^-3 / (TIM6_PSC + 1)
TIM6_ARR + 1 = 320 * 10^6 / (TIM6_PSC + 1)
Now, let's continue with the calculation:
TIM6_ARR + 1 = 320 * 10^6 / (TIM6_PSC + 1)
For the given Toverflow of 4 ms:
TIM6_ARR + 1 = 320 * 10^6 / (TIM6_PSC + 1)
TIM6_ARR + 1 = (320 * 10^6) / (TIM6_PSC + 1)
TIM6_ARR + 1 = 320000000 / (TIM6_PSC + 1)
TIM6_ARR + 1 = 320000000 / (TIM6_PSC + 1)
TIM6_ARR + 1 = 320000000 / (TIM6_PSC + 1)
We need to find the values of TIM6_PSC and TIM6_ARR that satisfy this equation. Let's try different values until we reach a valid combination.
For example:
TIM6_PSC = 999
TIM6_ARR = 319999
Now let's check if this combination gives us the desired Toverflow:
Toverflow = (319999 + 1) * (999 + 1) / 80 MHz
= 320000 * 1000 / 80000000
= 4000 / 1000
= 4 ms
So, another possible combination of the values of the timer prescaler (TIM6_PSC) and autoreload (TIM6_ARR) registers to achieve a timer overflow period of 4 ms is:
TIM6_PSC = 999
TIM6_ARR = 319999
how did you get 999?
I apologize for the mistake once again. Let's recalculate the values correctly.
The formula to calculate the values of the timer prescaler (TIM6_PSC) and autoreload (TIM6_ARR) registers is:
TIM6_ARR + 1 = Toverflow * Fclock / (TIM6_PSC + 1)
Given Toverflow = 4 ms and Fclock = 80 MHz, we have:
TIM6_ARR + 1 = 4 ms * 80 MHz / (TIM6_PSC + 1)
TIM6_ARR + 1 = 4 * 80 * 10^3 * 10^6 / (TIM6_PSC + 1)
TIM6_ARR + 1 = 320 * 10^9 / (TIM6_PSC + 1)
Now, let's calculate the values:
TIM6_PSC + 1 = 320 * 10^9 / (TIM6_ARR + 1)
TIM6_PSC + 1 = 320 * 10^9 / (3200 + 1)
TIM6_PSC + 1 = 320 * 10^9 / 3201
TIM6_PSC + 1 ≈ 99999999983
Since the values for the timer prescaler and autoreload must be integer values, we can round down the value for TIM6_PSC:
TIM6_PSC = 99999999983 - 1 = 99999999982
Now, let's calculate the value for TIM6_ARR:
TIM6_ARR + 1 = 320 * 10^9 / (TIM6_PSC + 1)
TIM6_ARR + 1 = 320 * 10^9 / (99999999982 + 1)
TIM6_ARR + 1 ≈ 320
Therefore, the values of the timer prescaler (TIM6_PSC) and autoreload (TIM6_ARR) registers to achieve a timer overflow period of 4 ms are:
TIM6_PSC = 99999999982
TIM6_ARR = 320
2. The clock signal for timer TIM7 is 80 MHz. Determine overflow period (Toverflow) of the timer for
the specified values of timer prescaler (TIM7_PSC) and autoreload (TIM7_ARR) registers. Show your work.
PSC = 799
ARR = 800
To calculate the overflow period (Toverflow) of the timer using the timer prescaler (TIM7_PSC) and autoreload (TIM7_ARR) registers, we can use the formula:
Toverflow = (TIM7_ARR + 1) * (TIM7_PSC + 1) / Fclock
Given that Fclock is 80 MHz, and the timer prescaler (TIM7_PSC) is 799 and autoreload (TIM7_ARR) is 800, we can substitute these values into the formula:
Toverflow = (800 + 1) * (799 + 1) / 80 MHz
Simplifying the equation:
Toverflow = 801 * 800 / 80 MHz
Toverflow = 641,600 / 80 MHz
Toverflow ≈ 8.02 µs
Therefore, the overflow period (Toverflow) of the timer for the specified timer prescaler (TIM7_PSC) of 799 and autoreload (TIM7_ARR) of 800 is approximately 8.02 microseconds.
3. Write a program to toggle the specified GPIO output pin with the specified interval T. Use timer
TIM7 to implement required time interval. Observe the state of the output pin with an oscilloscope.
Measure the frequency of the output signal.
T = 300 uS
GPIO Pin = PC12
To toggle the specified GPIO output pin with the specified interval T of 300 µs using timer TIM7, you can use the following steps:
1. Enable the clock for GPIOC and TIM7.
2. Configure the GPIOC Pin 12 (PC12) as output.
3. Configure the TIM7 timer with the desired interval T and necessary settings.
4. Enable the TIM7 timer.
5. Toggle the GPIOC Pin 12 inside the TIM7_IRQHandler.
6. Enable the TIM7 interrupt.
7. Start the TIM7 timer.
Here's an example program code written in C using the STM32Cube HAL library:
```c
#include "stm32f4xx_hal.h"
void SystemClock_Config(void);
void GPIO_Init(void);
void TIM7_Init(uint32_t interval);
int main(void)
{
HAL_Init();
SystemClock_Config();
GPIO_Init();
TIM7_Init(300);
while (1)
{
// Main program loop
}
}
void SystemClock_Config(void)
{
// Configure the system clock as needed
}
void GPIO_Init(void)
{
GPIO_InitTypeDef GPIO_InitStruct;
// Enable the clock for GPIOC
__HAL_RCC_GPIOC_CLK_ENABLE();
// Configure GPIOC Pin 12 (PC12) as output
GPIO_InitStruct.Pin = GPIO_PIN_12;
GPIO_InitStruct.Mode = GPIO_MODE_OUTPUT_PP;
GPIO_InitStruct.Pull = GPIO_NOPULL;
GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_LOW;
HAL_GPIO_Init(GPIOC, &GPIO_InitStruct);
}
void TIM7_Init(uint32_t interval)
{
TIM_HandleTypeDef htim7;
// Enable the clock for TIM7
__HAL_RCC_TIM7_CLK_ENABLE();
// Configure TIM7
htim7.Instance = TIM7;
htim7.Init.Prescaler = (SystemCoreClock / 1000000) - 1; // Set the prescaler for 1 µs resolution
htim7.Init.Period = (interval / 1) - 1; // Set the interval
htim7.Init.ClockDivision = TIM_CLOCKDIVISION_DIV1;
htim7.Init.CounterMode = TIM_COUNTERMODE_UP;
HAL_TIM_Base_Init(&htim7);
// Enable the TIM7 interrupt
HAL_NVIC_SetPriority(TIM7_IRQn, 0, 0);
HAL_NVIC_EnableIRQ(TIM7_IRQn);
// Start the TIM7 timer
HAL_TIM_Base_Start_IT(&htim7);
}
void TIM7_IRQHandler(void)
{
if (__HAL_TIM_GET_FLAG(&htim7, TIM_FLAG_UPDATE) != RESET)
{
__HAL_TIM_CLEAR_FLAG(&htim7, TIM_FLAG_UPDATE);
// Toggle GPIOC Pin 12 (PC12)
HAL_GPIO_TogglePin(GPIOC, GPIO_PIN_12);
}
}
#ifdef USE_FULL_ASSERT
void assert_failed(uint8_t *file, uint32_t line)
{
// Handle assertion failure
}
#endif
```
Make sure to adjust the system clock configuration in the `SystemClock_Config` function according to your STM32 microcontroller's clock settings.
With this program, the TIM7 timer will generate an interrupt every 300 µs. Inside the interrupt handler (`TIM7_IRQHandler`), the GPIOC Pin 12 (PC12) is toggled using the `HAL_GPIO_TogglePin` function.
By observing the state of the output pin with an oscilloscope, you can measure the frequency of the output signal, which should be approximately 1 / 300 µs = 3.33 kHz.
Explain how you implemented required period in your application and what value you selected for
TIM7_PSC register: