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MSP430 LaunchPad, 74HC595, Four 7 Segment Displays


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I'll assume you need some rest (grin), and I apologize if I made you feel a little defensive. That was not my intention Sir.

 

Hopefully, someone gleaned some insight into the use of a switch state latch and parallel switch state logic (a worthy subject by itself).

 

Take care. Have fun.

 

Cheerful regards, Mike McLaren, K8LH

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No you didn't. Constructive critique is always a good thing, that's how we learn. I would probably reuse that piece over and over and then I would be surprised why stuff doesn't work. And I would assume that my code is fine. That's why we should have peer reviews.

 

73

 

Rob

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Well Rob, there's still a couple things wrong with that section. Then there's your misconceptions about debouncing (grin). But how about if we save those discussions for another day? I don't want to wear out my welcome (lol)...

 

Vy 73, Mike, K8LH

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Ha, ha, yeah, I really need the rest, or test my changes before posting.

Since switchReady is int, we need to either change it (and the switchStatus) to char

unsigned char switchReady = 0;            // when BITn is 0, means switch is unstable H->L or L->H
unsigned char switchStatus = 0;            // pressed or released

or change if statement

if(switchReady == 0xFFFF)

As I wrote before, I had that code in another project where I used 16 switches and full USISR register (hence int) but in my if statement I only needed few of them tested.

 

Not sure what you mean by misconceptions about de-bouncing though. Again, as I wrote before, this is just an example of how it could be done. Someone might have a requirement to scan every 5ms, or use switches that have long bounce time, or that all switches must be in sync. I wish I had more time to elaborate and make some drawings, but I think we can leave it at that. Is it perfect, no, is it needed for this particular example, probably not, it can be removed.

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  • 1 year later...
  • 4 weeks later...

The 74595 shift registers can be replaced by a single chip max 7221. It can drive up to 8 seven segments and uses SPI to communicate to msp430. It saves quite a few I/o pins. Price wise, it's about the same price too ( even cheaper, if we buy from china. I just put an order to purchase 10 pcs of the chip for total of $6 including shipping)

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  • 8 years later...

İ will use 8 digit 7segment and i need to implement your code for 8 digit. Also first 4 digit will show something other 4 digit will show temprature. So how can i change your code? İ couldnt understand excatly.

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