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I want to interface the 6811 ports directly to CMOS IC's. Is it OK to do that and does it cause any problems?

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No problem. Why not HCMOS ? Roberto Guillermo Berner Boolean General ICQ 119529928 54 11 4308 3500 54 11 4308 3700 15 5122 6095 ----- Original Message ----- From: scan_expert To: Sent: Monday, October 21, 2002 11:37 PM Subject: [m68HC11] Interfacing with CMOS IC I want to interface the 6811 ports directly to CMOS IC's. Is it OK to do that and does it cause any problems? Yahoo! Groups Sponsor ADVERTISEMENT To unsubscribe from this group, send an email to: Your use of Yahoo! Groups is subject to the Yahoo! Terms of Service. [Non-text portions of this message have been removed]

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Hello¡¡ I've implemented in my 68HC11 home-made evaluation board the CMOS version of the Three-Port expander 8255, it is, the 82C55. I haven't experienced any type of conflict on the propagation times or CMOS-TTL incompabilities. On the other hand, I replaced the 74HC00, first, with the 4011 (Quad NAND CMOS), and then with 4093 (Quad NAND CMOS with Trigger-Schmitt inputs). None of these combinations really worked. I don't know if the problem was the propagation times or incompabilities due to use different technologies. --------------------------------- Yahoo! Messenger Nueva versión: Webcam, voz, y mucho más ¡Gratis! [Non-text portions of this message have been removed]

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Mario, Depending on the clock frequency, CMOS won't work because of its 250 ns propagation delay vs 25 ns or less of a TTL LSTTL or HCMOS gate. Regards, Roberto Guillermo Berner Boolean General ICQ 119529928 54 11 4308 3500 54 11 4308 3700 15 5122 6095 ----- Original Message ----- From: mario lopez To: Sent: Tuesday, October 22, 2002 7:28 PM Subject: Re: [m68HC11] Interfacing with CMOS IC Hello¡¡ I've implemented in my 68HC11 home-made evaluation board the CMOS version of the Three-Port expander 8255, it is, the 82C55. I haven't experienced any type of conflict on the propagation times or CMOS-TTL incompabilities. On the other hand, I replaced the 74HC00, first, with the 4011 (Quad NAND CMOS), and then with 4093 (Quad NAND CMOS with Trigger-Schmitt inputs). None of these combinations really worked. I don't know if the problem was the propagation times or incompabilities due to use different technologies. --------------------------------- Yahoo! Messenger Nueva versión: Webcam, voz, y mucho más ¡Gratis! [Non-text portions of this message have been removed] Yahoo! Groups Sponsor ADVERTISEMENT To unsubscribe from this group, send an email to: Your use of Yahoo! Groups is subject to the Yahoo! Terms of Service. [Non-text portions of this message have been removed]

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If a delay subroutine is written in the program, can the 250 ns propagation delay CMOS IC problem be solved?

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> If a delay subroutine is written in the program, can the 250 ns > propagation delay CMOS IC problem be solved? Probably, but you're unlikely to be able to find "standard" CMOS as slow as the old spec. Use the available HCMOS and you should have no problems.

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> If a delay subroutine is written in the program, can the 250 ns > propagation delay CMOS IC problem be solved? As others have pointed out, why don't you use HCMOS (74HCxx) chips. They are fast, much easier to source, come in many more flavours and probably less expensive than CMOS (i.e., 40xx). Bfn, Bob Furber __________________________________________________________ Connect your micro to the internet the easy way www.microcommander.com Microcontroller with an obscenity of I/O & features ..in a small footprint www.steroidmicros.com __________________________________________________________

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