External flip-flop chip to synchronize an external asynchronous input

In summary, the conversation discusses the use of an external flip-flop chip to synchronize an external asynchronous input into a microcontroller. The main concern is how to provide a clock for the FF chip that runs at the same rate as the microcontroller's system clock. Possible solutions include generating a wave from PWM or using a separate crystal oscillator chip. However, it is later discovered that the microcontroller's core has the capability to provide a clock output on a pin. The conversation also mentions the importance of using 2 FFs to synchronize the signal and the use of VHDL for a FFT project.
  • #1
EvLer
458
0
Hello everyone,

I am using an external flip-flop chip to synchronize an external asynchronous input into a microcontroller. So, what I am wondering about is how to provide a clock into the FF chip... it has to run at the same rate as the system clock of the microcontroller. Is there a way to take the oscillator clock out on a pin? ... in general that is...
I was also thinking of generating a wave from PWM with unscaled clock and rout it to the FF... or would i have to have a separate crystal oscillator chip? The microcontroller is motorolla 68hc12.
Thanks in advance.
 
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  • #2
nevermind... found something in the pile of documentation on the core where i can take the clock out on a pin...
 
  • #3
Remember that it takes 2 FFs to synchronize the signal. Is the 2nd FF the input into the uC?
 
  • #4
berkeman said:
Remember that it takes 2 FFs to synchronize the signal. Is the 2nd FF the input into the uC?

:biggrin: :biggrin: yeah, berkeman... THAT i have learned on my own mistake and will not forget. For FFT project i am writting flip-flops in vhdl, no externals.

But this one is a project on speed-detection using microcontroller, in which case i have to use external chips. Seems like it is possible to 'rout out' a clock from the core.
 

1. What is an external flip-flop chip?

An external flip-flop chip is a semiconductor device that is used to store and transmit data. It consists of two states, either 0 or 1, which correspond to the binary digits of 0 and 1. It is commonly used in digital logic circuits to synchronize data.

2. How does a flip-flop chip work?

A flip-flop chip works by using a clock signal to control the timing of data transmission. When the clock signal transitions from low to high, the input data is captured and stored in the flip-flop's memory. When the clock signal transitions from high to low, the stored data is then transmitted to the output. This synchronization process ensures that the data is transmitted accurately.

3. What is an external asynchronous input?

An external asynchronous input is a signal that is not controlled by a clock. It can transition at any time and is not synchronized with the clock signal used by the flip-flop chip. This can cause issues with data transmission as the flip-flop may capture the input signal at the wrong time.

4. How does an external flip-flop chip synchronize an external asynchronous input?

To synchronize an external asynchronous input, the flip-flop chip uses a technique called "edge-triggering". This means that the data is only captured and transmitted when the clock signal transitions from one state to another. This ensures that the data is transmitted at the correct time and reduces the chances of errors occurring.

5. What are the benefits of using an external flip-flop chip to synchronize an external asynchronous input?

The main benefit of using an external flip-flop chip is that it ensures accurate data transmission by synchronizing the external asynchronous input with the clock signal. This is important in digital logic circuits where data accuracy is crucial. Additionally, flip-flop chips are relatively inexpensive and widely available, making them a cost-effective solution for data synchronization.

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