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Hi booglybob Welcome to electronics point! I like you username!
Why don't you want to use ICs? It's going to be really hard to do without them, and really pricey.
Dan
Why don't you want to use ICs? It's going to be really hard to do without them, and really pricey.
Dan
Last edited:
KrisBlueNZ
Sadly passed away in 2015
Without ICs? And you're making a handheld game? Are you a masochist?
KrisBlueNZ
Sadly passed away in 2015
The CD4015 (http://www.digikey.com/product-detail/en/CD4015BE/296-2035-5-ND/67249) does not need programming. It's a dual 4-bit shift register with parallel outputs. Here's how you use it to drive up to eight LEDs.
Tie both Reset inputs together. They must be driven high briefly when the game starts, to enable all of the lives. Tie both clock inputs together and drive them from a pulse that goes high each time you want to count off one life, then returns low. Tie the data input of the first shift register high, and tie the data input of the second shift register to the Q4 output of the first.
Connect your LEDs between the shift register outputs and VDD, with current limiting resistors.
When the circuit is reset by an active high level on the Reset inputs, all shift register outputs will go low, and all LEDs will light up, showing that all lives are available.
When the first rising edge occurs on the clock, a high level will be clocked into the first section of the first shift register, and the corresponding LED will go out, indicating that one life has been lost.
As further clock pulses are received, further high levels are clocked through the shift registers, causing the LEDs to go out in sequence. Once the last LED has gone out, further clocks will have no more effect until the shift registers are reset again.
There are other suitable devices in the 74 logic family as well. Connection details will be slightly different. Search for serial-input, parallel-output shift registers with reset input.
Tie both Reset inputs together. They must be driven high briefly when the game starts, to enable all of the lives. Tie both clock inputs together and drive them from a pulse that goes high each time you want to count off one life, then returns low. Tie the data input of the first shift register high, and tie the data input of the second shift register to the Q4 output of the first.
Connect your LEDs between the shift register outputs and VDD, with current limiting resistors.
When the circuit is reset by an active high level on the Reset inputs, all shift register outputs will go low, and all LEDs will light up, showing that all lives are available.
When the first rising edge occurs on the clock, a high level will be clocked into the first section of the first shift register, and the corresponding LED will go out, indicating that one life has been lost.
As further clock pulses are received, further high levels are clocked through the shift registers, causing the LEDs to go out in sequence. Once the last LED has gone out, further clocks will have no more effect until the shift registers are reset again.
There are other suitable devices in the 74 logic family as well. Connection details will be slightly different. Search for serial-input, parallel-output shift registers with reset input.
KrisBlueNZ
Sadly passed away in 2015
No problem 
