Post by thread:pic17c42

WF AUTOMA_AO <spam_OUTPICLISTTakeThisOuTMITVMA.MIT.EDU> wrote: > I intend to use the PIC17C42 in the Microprocessor Mode, having 8K > of EPROM program and 8K of RAM data and have some doubts: > > -What is the LSB and MSB memory that is described in Databook? mIGUEL: The PIC17C42's program memory is 16 bits wide; the LSB and MSB refer to the two 8-bit halves of each 16-bit word. > Must i have to care the Even and Odd address? > Must i have 2 EPROM and 2 RAM (for odd and even Address), like the > the 8086 microprocessor, or only use the configuration like 8032 Von > Neumann configuration, with a latch for MSB address! If you're using 8-bit RAMs and EPROMs, you need two of each in order to provide both halves of each program-memory word... It's not EXACTLY like the 8086's even/odd addressing, since the 17C42 treats every pair of bytes as two halves of the SAME address, but it's similar. The address lines are NOT multiplexed as they are on the 8032. > If someone have a circuit, i will be happy! The 17C4x data book contains a simple diagram for using 8-bit memories; if you buy 16-bit memories, your circuit becomes much simpler. One thing to watch for: The 17C42 wants to talk to its memory at VERY high speeds... You may have some difficulty finding memories and latches that can keep up, especially if your address decoding logic is complicated. -Andy === Andrew Warren - .....fastfwdKILLspam@spam@ix.netcom.com === Fast Forward Engineering - Vista, California === http://www.geocities.com/SiliconValley/2499

On Wed, 15 Oct 1997 17:06:39 -0700 WF AUTOMA=?iso-8859-1?Q?=C7=C3O ?= <wfKILLspamAMBIENTE.COM.BR> writes: >HI AGAIN! > > I intend to use the PIC17C42 in the Microprocessor Mode, >having >8K of EPROM program and 8K of RAM data and have some doubts: > > -What is the LSB and MSB memory that is described in Databook? > The program memory must be 16 bits wide. This means 2 nx8 bit devices. 16-bit EPROMs are available, but not very common. The LSB and MSB apply only for the internal to the PIC operation of loading the data in and out of the data table latch, which must be done 8 bits at a time since the file registers are 8 bits. >Must i have to care the Even and Odd address? No. There is no signifigance of even and odd addresses. All addresses are word addresses, and all reads and writes are 16 bits at a time. Logic typically used with the 8086 to write low 8 bits, high 8 bits, or all 16 bits isn't applicable here. If the software is to write 8 bits at a time to 16-bit RAM, it must do a TABLRD instruction first to read the other 8 bits in the word so they won't be changed. >Must i have 2 EPROM and 2 RAM (for odd and even Address), like the the >8086 microprocessor, or only use the configuration like 8032 Von >Neumann >configuration, with a latch for MSB address! You can use memory only 8 bits wide (or any width for that matter) for data-only storage. The software can ignore the unavailable bits. But, any code to be executed must be stored 16 bits wide so the PIC can get the complete instruction in 1 read cycle. The external circuit has to latch *all* bits of the address. > > If someone have a circuit, i will be happy! The circuit is easy to describe, but tedious to wire. Ports C and D are the 16-bit multiplexed AD bus. Connect it to the I/O pins of the memory chips, and to the inputs of two 74HC373 8-bit latch chips. Pin 30 (ALE/RE0) to the LE pins of the latches. Tie the 373's output enable pins low. The outputs of the 373's go to the address inputs of the memory chips. If you have more than one set of memory chips (e.g. EPROM and RAM chips), send some of the high addresses to an address decoder that controls the CE lines so only one pair of chips is enabled at a time. If there's only one pair of memory chips it's OK to tie CE on the chips low (though this will make them draw more power). OE and WE of the memories are controlled directly from the PIC pins 29 and 28 respectively. If you intend to operate the PIC at medium to high speed, check the timing carefully. Fast memory chips are required. If I were faced with an application that needed so much code or fast data memory that external chips are required I probably wouldn't use the PIC17. The 8051 type chips or the 68HC ones are slower than PIC, but the external memory is only 8 bits wide so a lot less hardware and wiring is required.

At 05:06 PM 10/15/97 -0700, you wrote: >HI AGAIN! > > I intend to use the PIC17C42 in the Microprocessor Mode, having >8K of EPROM program and 8K of RAM data and have some doubts: > > -What is the LSB and MSB memory that is described in Databook? because you need 16 data bus(2 EPROM, 2 RAM) > >Must i have to care the Even and Odd address? MPLAB can do this(split hex) >Must i have 2 EPROM and 2 RAM (for odd and even Address), like the the >8086 microprocessor, or only use the configuration like 8032 Von Neumann >configuration, with a latch for MSB address! the address just same, only data bus > > If someone have a circuit, i will be happy! yes, just download schematics(in PDF) from my homepage. goodluck http://www.poboxes.com/f f

Frans Gunawan wrote: {Quote hidden}> > At 05:06 PM 10/15/97 -0700, you wrote: > >HI AGAIN! > > > > I intend to use the PIC17C42 in the Microprocessor Mode, having > >8K of EPROM program and 8K of RAM data and have some doubts: > > > > -What is the LSB and MSB memory that is described in Databook? > because you need 16 data bus(2 EPROM, 2 RAM) > > > > >Must i have to care the Even and Odd address? > MPLAB can do this(split hex) > > >Must i have 2 EPROM and 2 RAM (for odd and even Address), like the the > >8086 microprocessor, or only use the configuration like 8032 Von Neumann > >configuration, with a latch for MSB address! > the address just same, only data bus > > > > > If someone have a circuit, i will be happy! > > yes, just download schematics(in PDF) from my homepage. > goodluck > http://www.poboxes.com/f > f Frans! Excelent your circuit! I will try to build your circuit, but my problem is that there is not documented the LOGIC OF GAL! I don't know that address that you choose for the I/O! Miguel.

Frans Gunawan wrote: {Quote hidden}> > At 05:06 PM 10/15/97 -0700, you wrote: > >HI AGAIN! > > > > I intend to use the PIC17C42 in the Microprocessor Mode, having > >8K of EPROM program and 8K of RAM data and have some doubts: > > > > -What is the LSB and MSB memory that is described in Databook? > because you need 16 data bus(2 EPROM, 2 RAM) > > > > >Must i have to care the Even and Odd address? > MPLAB can do this(split hex) > > >Must i have 2 EPROM and 2 RAM (for odd and even Address), like the the > >8086 microprocessor, or only use the configuration like 8032 Von Neumann > >configuration, with a latch for MSB address! > the address just same, only data bus > > > > > If someone have a circuit, i will be happy! > > yes, just download schematics(in PDF) from my homepage. > goodluck > http://www.poboxes.com/f > f -- THANK'S! cOULD YOU GIVE THE DESCRIPTION OF CIRCUIT INTO THE GAL? mIGUEL.

At 08:29 PM 10/16/97 -0700, you wrote: >Frans Gunawan wrote: >I will try to build your circuit, but my problem is that there is not documented > the LOGIC OF >GAL! I don't know that address that you choose for the I/O! here is the equation for gal16v8: BA15 BA14 BA13 RD WR BA2 BA1 BA0 NC GND RESL RESH RAM IOADDRLO IOADDRHI DATAIN DATAOUT NC 259 VCC @DEFINE IOREG "/(BA15 * BA14 * BA13)" @UES FGUNAWAN EQUATIONS /RAM = BA15 * /BA14 * /BA13 /DATAIN = /IOREG* /RD /DATAOUT = /IOREG* /WR * /BA2 * BA1 * /BA0 /IOADDRLO = /IOREG* /WR * /BA2 * /BA1 * /BA0 /IOADDRHI = /IOREG* /WR * /BA2 * /BA1 * BA0 /259 = /IOREG* /WR * BA2 RESH = /RESL goodluck http://www.poboxes.com/f f

Frans Gunawan wrote: {Quote hidden}> > At 08:29 PM 10/16/97 -0700, you wrote: > >Frans Gunawan wrote: > >I will try to build your circuit, but my problem is that there is not > documented > > the LOGIC OF > >GAL! I don't know that address that you choose for the I/O! > > here is the equation for gal16v8: > BA15 BA14 BA13 RD WR BA2 BA1 BA0 NC GND > RESL RESH RAM IOADDRLO IOADDRHI DATAIN DATAOUT NC 259 VCC > @DEFINE IOREG "/(BA15 * BA14 * BA13)" > @UES FGUNAWAN > EQUATIONS > > /RAM = BA15 * /BA14 * /BA13 > /DATAIN = /IOREG* /RD > /DATAOUT = /IOREG* /WR * /BA2 * BA1 * /BA0 > /IOADDRLO = /IOREG* /WR * /BA2 * /BA1 * /BA0 > /IOADDRHI = /IOREG* /WR * /BA2 * /BA1 * BA0 > /259 = /IOREG* /WR * BA2 > RESH = /RESL > > goodluck > http://www.poboxes.com/f > f Thank's! I will verify this week! Miguel.