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Hi, Has anyone used the 4094 serial to parallel latch with the HC12 SPI buss - is it compatable (out of box)? Please advise Thanks Frank |
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SPI 8 bit data latch
Started by ●September 21, 2003
Reply by ●September 21, 20032003-09-21
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In a message dated 9/21/03 6:14:58 AM Eastern Daylight Time, writes: Has anyone used the 4094 serial to parallel latch with the HC12 SPI buss - is it compatable (out of box)? I've used ls165 for inputs, we use an allegro 5821 for outputs (hi current) but I've seen folks use hc595 for outputs |
Reply by ●September 21, 20032003-09-21
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Hi, Interesting ICs Allegro has. However I dont require that much current. What I require is to increase the output driver for the port pins of the DP256. So I most likely will use TIs dual buffer little logic SN74VC2G241 as the bi-directional drivers per port and the 4094 to latch the data direction to increase output drive and still reserve the programmable bi-direction capability of the port pins. I was hoping to find something like a single port version of the venerable 8255, could not find any. I other words a programmable data direction latch on a bit level. Frank ----- Original Message ----- From: <> To: <> Sent: Sunday, September 21, 2003 6:40 AM Subject: Re: [68HC12] SPI 8 bit data latch > In a message dated 9/21/03 6:14:58 AM Eastern Daylight Time, > writes: > Has anyone used the 4094 serial to parallel latch with the HC12 SPI buss - is > it compatable (out of box)? > I've used ls165 for inputs, we use an allegro 5821 for outputs (hi current) > but I've seen folks use hc595 for outputs > > -------------------- > > ">http://docs.yahoo.com/info/terms/ |
Reply by ●September 21, 20032003-09-21
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In a message dated 9/21/03 6:23:29 PM Eastern Daylight Time, writes: Interesting ICs Allegro has. However I dont require that much current. What I require is to increase the output driver for the port pins of the DP256. So I most likely will use TIs dual buffer little logic SN74VC2G241 as the bi-directional drivers per port and the 4094 to latch the data direction to increase output drive and still reserve the programmable bi-direction capability of the port pins. I was hoping to find something like a single port version of the venerable 8255, could not find any. I other words a programmable data direction latch on a bit level. ========================================= well, if you hook up an LS165 to get 8 inputs on the miso, and an HC595 to get 8 ttl outputs on the mosi, and hook em in series, when you write to the output chip, you'll read the input chip for 'free'. |
Reply by ●September 21, 20032003-09-21
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Hi, Not a bad idea - thanks. However (in my case) strobing the inputs, means loosing real time functionality. Such as measuring input periods, interrupt response etc. So in other words, I need ALL the original functionality of the port properties. Frank ----- Original Message ----- From: <> To: <> Sent: Sunday, September 21, 2003 3:39 PM Subject: Re: [68HC12] SPI 8 bit data latch > In a message dated 9/21/03 6:23:29 PM Eastern Daylight Time, > writes: > Interesting ICs Allegro has. However I dont require that much current. What > I require is to increase the output driver for the > port pins of the DP256. So I most likely will use TIs dual buffer little > logic SN74VC2G241 as the bi-directional drivers per port > and the 4094 to latch the data direction to increase output drive and still > reserve the programmable bi-direction capability of the port pins. I was > hoping to find something like a single port version of the venerable 8255, > could not find any. I other words a programmable data direction latch on a > bit level. > ========================================= > well, if you hook up an LS165 to get 8 inputs on the miso, and an HC595 to > get 8 ttl outputs on the mosi, and hook em in series, when you write to the > output chip, you'll read the input chip for 'free'. > > -------------------- > > ">http://docs.yahoo.com/info/terms/ |
Reply by ●September 21, 20032003-09-21
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If cost is no object, and you want to maintain bit-programmable I/O
sense, you could always use a small EPLD, like a 7064S from Altera. By setting up registers internal to the EPLD to control the output enables on the 'hc12 versus external sides of the chip, you could improve the per-pin drive to (if I remember correctly) 24 mA per pin. Other manufacturers (Xilinx, Cypress, Lattice, etc.) would provide similar alternatives. We've often used EPLDs as port expanders for both SPI-type and parallel I/O applications. Not as cheap as simple single chips like an 'HC245, but gives you bit-programmable data direction, either fixed in the EPLD setup or under 'hc12 control. /s/jar () http://www.mtritter.org EMAIL DISCLAIMER Please Note: The information contained in this message may be privileged and confidential, protected from disclosure, and/or intended only for the use of the individual or entity named above. If the reader of this message is not the intended recipient, or an employee or agent responsible for delivering this message to the intended recipient, you are hereby notified that any disclosure, distribution, copying or other dissemination of this communication is strictly prohibited. If you received this communication in error, please immediately reply to the sender, delete the message and destroy all copies of it. Thank You |
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Reply by ●September 21, 20032003-09-21
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Hi Alan, > If cost is no object, and you want to maintain > bit-programmable I/O sense, > you could always use a small EPLD, like a 7064S from Altera. > By setting up > registers internal to the EPLD to control the output enables > on the 'hc12 > versus external sides of the chip, you could improve the > per-pin drive to > (if I remember correctly) 24 mA per pin. Interesting! I am particularly interested in how you connect to the CPLD and how you access it. Do you connect a high address line and access it as far memory? Bfn, Bob Furber __________________________________________________________ HMI software brings true interactivity to microcontrollers www.microcommander.com __________________________________________________________ |
Reply by ●September 22, 20032003-09-22
