Thread View: comp.robotics
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Started by Brad Smallridge
Tue, 12 Jan 1993 22:13
PICs
Author: Brad Smallridge
Date: Tue, 12 Jan 1993 22:13
Date: Tue, 12 Jan 1993 22:13
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PIC UPDATE Last month I wrote an article on PICs, Programmable Integrated Circuits, and placed the article in several robot newsletters and also on USENET, an electronic news service. The response, especially from USENET, has been useful. First of all, we can forget about the Motorola 68L705. I was told that after the current supply of parts is depleted, the 68L705 will no longer be available. On the other hand, Microchip is strengthening its PIC line with an advancement over the PIC16C5x series called the PIC16C71 including these new additions: * Four 8-bit A/D Inputs * Four Interrupt Sources * Eight Level Hardware Stack * Programmable On-board Pull-up Resistors The addition of Analog to Digital Converter Inputs makes the chip much more attractive. I can imagine several more applications using the analog capabilities. Too bad there is no Digital to Analog Converter. The external Interrupt allows an outside occurrence to trigger an action by the PIC as well as an internal timer Interrupt capability. The stack is eight deep getting rid of an annoying limitation on the 16C5x series that are only two deep. And the programmable Pull-up simplyallows you to use fewer components in your design -- a nice touch. Microchip also expanded the internal instruction word from 12 bits to 14 bits. This cleaned up the instruction set. For example, the Jump instruction can go anywhere in the 1K program memory without regard to what page it's on. Also the registers are all addressable without selecting register banks. These improvements create cleaner and faster code. The new PIC requires a programmer upgrade from Parallax which cost $99 and is available now. My costs now are up to about $350 total. There are no Parallax ICE or emulators available yet. The PIC16C71 chips themselves are hard to get and right now and are only available on a sample basis. I suggest you call Microchip and get information on the office nearest you. Microchip Technology (602)963-7373 Microchip (Sunnyvalle Office)(408)436-7950 Trinity Technologies (Sunnyvalle) (408)733-9000 Parallax,Inc (916)721-8217 Brad Smallridge Phone (415)550-0588 FAX (415)550-0411 BBS (415)648-6427 EMAIL bsmall@holonet.net
Re: PICs
Author: john r strohm
Date: Tue, 12 Jan 1993 23:43
Date: Tue, 12 Jan 1993 23:43
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In article <C0rHqz.2Jq@iat.holonet.net> bsmall@iat.holonet.net (Brad Smallridge) writes: >First of all, we can forget about the Motorola 68L705. I am not familiar with the 68L705. I am familiar with the 68HC705K1, which certainly qualifies as a PIC. Is this the same part? Second, can you give me a contact address/phone number for Microchip? I would REALLY like to get some databooks from them.
Re: PICs
Author: Rodney Radford
Date: Wed, 13 Jan 1993 05:04
Date: Wed, 13 Jan 1993 05:04
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bsmall@iat.holonet.net (Brad Smallridge) writes: >PIC UPDATE >First of all, we can forget about the Motorola 68L705. I >was told that after the current supply of parts is depleted, >the 68L705 will no longer be available. On the other hand, >Microchip is strengthening its PIC line Motorla is dropping several members of the 68705 family, but from what I remember of the last list, there were still over 20 variations of this part still in full production (in fact the latest member, the 68705K1 was just announced last summer). Yes, the Microchip PIC parts are nice, but they require that you put out money to buy a programmer from Microchip (or Parallax has one too) for about $200, or use one of the $1K+ universal programmers. Both are kind of expensive for the typical electronics experimenter. However, if you are REAL NICE to Microchip, and get the RIGHT FE on the phone, they MAY give you a copy of the programming specs - with that it is possible to easily build a IBM/PC controllable programmer for under $20 (for the 16c5x series). I understand that the 16c71 programs via a serial interface, and that the programming specs are in the normal data sheets. If so, great - but I haven't seen the specs to verify this. On the other hand, many of the Motorola 68705 family are self programming, where they just copy their internal EPROM image from another EPROM. So you just program the master EPROM in your normal programmer, stick it in a very simple circuit, and it does the rest (and the circuit schematics are available from Motorola, along with PC boards). Or if you were lucky enough to buy one of the 68705K1 evaluation kits last summer it only cost $50 for the programmer, a SLUSH development system (not quite as 'cool' as an ICE system), assembler, and one of their parts. And no, I have no ties to Motorola - I just like their 16705 line. Now if they would just get their act together and get me some 68705K1s I would be happy as I have been 'in the queue' since last July!!!! -- --- Rodney Radford || Computer Graphics/Imaging sasrer@unx.sas.com || SAS Institute, Inc. (919) 677-8000 x7703 || Cary, NC 27513
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