AVR Freaks

Greetings and Welcome to AVR Freaks,

I would start by writing down all the things that a chess clock does. There is a button that the players push, right? What happens when that button is pushed? Then, what happens while the timer runs? Then what happens when the timer times out?  Does it have to do anything else like indicate which player the timer is active for?

You might look in the tutorial section for tutorials on "state machine" or "finite state machine" or "FSM".

If you can make it so that one timeout interval fits all games, then you don't have to change the length of the interval, and it becomes really easy. If you have to be able to set that interval, then start out with the interval time as a variable. Once the timer is working, you can then figure out how to load different timer values into the machine, maybe via USB from another computer. That raises the complexity level pretty high for a starter-project, though.

Good luck on your project.

Jim

For the displays, is it allowed to use these ones? Two of these can be controlled from two wire interface known as I2C. But this means you have to use TM1637 library. 

As said above those display modules have their own little intelligent micro ("backpack") on board so the AVR you program will "talk" to them by sending commands like "set digit 2 to show a 9"and that kind of thing. The actual connection is either two wire (clock and data) known as inter-integrated-circuit (IIC or usually I²C) or three wire (clock, data out, data in) known as serial peripheral interface (SPI). Most AVR have separate internal blocks that can do I²C or SPI. So whatever display module you choose you should be covered but make sure to pick either a mega AVR or an Xmega AVR. Don't pick a Tiny AVR. They may look smaller, cheaper, less complex but they don't have things like I2C/SPI but a half arsed thing called USI that makes doing either MORE complicated.

In a previous post I said the display would be the most complex part of the design. It is. It's going to be quite a challenge if this is your first AVR project! 

At least using four grouped 7 segs with their own controller takes away some of the complexity. If you were trying to connect eight 7-seg displays direct to the AVR it would get very complex indeed! 

Use case is outdoor table tops or furniture; IIRC, some cities have chess table concrete furniture at parks.

Smart Alphanumeric Displays (Broadcom)

GH-2794P: Arndt Electronics : 7-Digit LCD Positive Reflective with 2 Decimal Points SMD : Opto & Illumination (Jameco)

mega48 drives a 3.5 digit segment LCD :

AN8103 AVR340: Direct Driving of LCD Using General Purpose IO using tinyAVR and megaAVR devices | Application Note | Microchip Technology

which are 13 mm high at Mouser :

3.5 LCD Numeric Display Modules – Mouser

In the midst of the AVRe+ shortage, mega329 are in stock.

ATMega329 | Octopart

with AVR Butterfly and a sale at Newark :

ATAVRBFLY | Octopart

XMEGA B has a character map segment LCD drive; am surprised at the stock level of this XMEGA as XMEGA are long lead time :

ATxmega64B | Octopart

XMEGA Lead Time, Dec'20 | AVR Freaks

edit :

Segmented LCD Solutions | Microchip Technology

I don't know Bascom but it might be an idea to see if the editor has a way to show line numbers. However in:

It is pretty evident that the line in red must be line 167 which is the line to which all four listed errors refer. So just red what it is telling you about that line:

"wrong data type"

"unknown variable"

"variable not dimensioned"

(ignore the last about "NEXT expected" - that is just a consequence of the first three errors).

Those errors are all talking about "Digit8". It's maybe not surprising as it's the only thing really mentioned on line 167 apart from standard BASIC keywords like "FOR" and "TO".

Again I don't know Bascom but it did not take me long to find:

https://avrhelp.mcselec.com/lang...

On that page you will read:

Before assigning a variable, you must tell the compiler about it with the DIM statement.

Dim b1 As Bit, I as Integer, k as Byte , s As String * 10

This is not unlike the C programming language too; before a variable can be used it must be declared in some way so that the language knows what type it is, how much storage to set aside for it  and how how to treat it in subsequent operations. Adding "+ 1" to a "byte" or "integer" is going to be quite different to performing "+ 1" in a string for example!

So clearly

Sub Buff_out(byval Disno As Byte)

For Digit8 = 1 To 8

Call Displ_write(digit8 , Seg_buff(disno , Digit8) , Disno)

Next
End Sub

needs to be:

Sub Buff_out(byval Disno As Byte)

Dim Digit8 As Byte

For Digit8 = 1 To 8

Call Displ_write(digit8 , Seg_buff(disno , Digit8) , Disno)

Next
End Sub

However, even before that is added perhaps alarm bells should have been ringing as there are clues here that this is NOT very well written code. A good programmer will use indentation to show the flow of execution. The fact that all the lines are left aligned suggests someone is sloppy and not putting much effort into the code so I would be suspicious of the code anyway. It probably should look more like:

Sub Buff_out(byval Disno As Byte)

    Dim Digit8 As Byte

    For Digit8 = 1 To 8
        Call Displ_write(digit8 , Seg_buff(disno , Digit8) , Disno)
    Next
End Sub

By the way, earlier in the code you will see an example:

Sub No_op(byval T As Byte)
 Local C As Byte
 Local H As Word

 H = 0
 For C = 1 To T
  Shiftout Ser_data , Ser_clk , H , 1 , 16 , 10
 Next C
End Sub

What this shows you is that there is an alternative to "Dim" which is "Local". Again, you would need to read more of that manual I just linked to but I imagine (a bit like local variables in C) that using "Local" instead of "Dim" just makes a more efficient (possibly!), more isolated/localised variable and is probably preferable to "Dim" which is more likely used for "global" variables. So the sub routine might be better as:

Sub Buff_out(byval Disno As Byte)

    Local Digit8 As Byte

    For Digit8 = 1 To 8
        Call Displ_write(digit8 , Seg_buff(disno , Digit8) , Disno)
    Next
End Sub

The fact that someone posted that code to a message board without having actually compiled/tested it (or they would have seen the same error you did) is, again, not a great sign.

Or perhaps use those huge red emergency stop buttons. They also have to be able to take a pounding because of their function, and would be easy to hit.