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Re: DSKY V3? [message #8476 is a reply to message #8474]

Sat, 17 April 2021 15:05

danwerner
Messages: 50
Registered: October 2015

Member

It would not be impossible to add in a way for the DSKY to be auto detected. . . . There are two open input pins on the 74LS148(u2) decoder that is used to scan the keyboard matrix. Today they are both tied to low, BUT . . . If we tied them to the LED output from the 74LS138(U1), you could toggle that output and then look for a corresponding input from the row decoder. Seems like a pretty simple change.

I do have the PCBs in and am building up a prototype now. I think for the next run I want to make three changes . . .

#1 I currently had five of the max7219 seven segment modules in stock, and I noticed when building that there are at least three different pinouts of those modules. So I think a jumper block would be appropriate so that almost any of the cheap pre-made modules will work.

#2 Seems like there should be a connector on the new DSKY that is compatible with the old SBC without making a custom cable. The new DSKY only needs 8 bits (4 in/4 out) and the new connector was designed to reflect this, but it might also be good to have the original connector on the board as well. I think a pass through connector would also be useful so that the rest of the ports can be used by other hardware.

#3 Wire up the LED output to the bit 6 and 7 inputs of the decoder to allow hardware detection

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[Message index]

		DSKY V3? By: lynchaj on Mon, 29 March 2021 07:47
		Re: DSKY V3? By: danwerner on Tue, 30 March 2021 07:21
		Re: DSKY V3? By: lynchaj on Tue, 30 March 2021 09:16
		Re: DSKY V3? By: danwerner on Thu, 01 April 2021 08:53
		Re: DSKY V3? By: lynchaj on Thu, 01 April 2021 12:06
		Re: DSKY V3? By: danwerner on Thu, 01 April 2021 13:32
		Re: DSKY V3? By: lynchaj on Thu, 01 April 2021 15:08
		Re: DSKY V3? By: Wayne W on Fri, 16 April 2021 16:12
		Re: DSKY V3? By: danwerner on Sat, 17 April 2021 15:05
		Re: DSKY V3? By: danwerner on Mon, 19 April 2021 09:00
		Re: DSKY V3? By: danwerner on Tue, 20 April 2021 06:23
		Re: DSKY V3? By: danwerner on Fri, 25 June 2021 16:04
		Re: DSKY V3? By: danwerner on Fri, 25 June 2021 16:18
		Re: DSKY V3? By: lynchaj on Mon, 05 July 2021 05:02
		Re: DSKY V3? By: lynchaj on Fri, 09 July 2021 07:16
		Re: DSKY V3? By: danwerner on Tue, 13 July 2021 11:21
		Re: DSKY V3? By: drj113 on Tue, 10 September 2024 18:34
		Re: DSKY V3? By: phil_g on Thu, 12 September 2024 12:20
		Re: DSKY V3? By: edzard on Tue, 13 July 2021 12:17

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