Hi Matt, Interfacing different logic families it's quite easy. The simplest way for input or output interfacing: - 3.3V to 5V nothing need (HI logic levels on 3.3V enough for driving a 5V input) - 5V/3.3V simple resistive divider or 1.8V forward series diode drop (assuming no huge rate data transfer) or series resistor folowed by a schottky diode clamped to +3.3V in conduction.
read the end of this material if something is not clear on the explanation above: http://ww1.microchip.com/downloads/en/DeviceDoc/01146B.pdf Vasile On 10/30/09, mattschinkel <[email protected]> wrote: > > > I need a 5v PIC because of other components I will use for my circuit, > so I must interface from 5v to 3v. any suggestions? > > On Oct 30, 10:07 am, William <[email protected]> wrote: > > Hi Matt, > > > > I'd recommend you choose a 3.3 volt picmicro, rather than trying to > > interface 3.3v parts to a 5 volt picmicro. It could be done, but why > > put yourself thru all of the hassle? > > > > About switching modes -- we may never find a generic solution for > > that, since there are so many chips out there, and they don't all > > quite behave the same way. Take a look at this web page, where this > > type of problem is being discussed (he calls it multi-slave > > configuration) http://elm-chan.org/docs/mmc/mmc_e.html > > > > I expect many projects will just have to use our JAL SPI library as a > > starting point for their own, custom, version of the library. It is > > unfortunate, but sometimes the most practical solution. We're only > > talking about a hand-full of lines of code anyway. > > > > William > > > > On Oct 29, 12:47 pm, mattschinkel <[email protected]> wrote: > > > > > > > > > What is the correct way to interface a 5v PIC input/output to a 3.3v > > > component? Asuming the pin will change from input to output throughout > > > the program. > > > > > I will make a tutorial for this chip but need a correct circuit. > > > Currently I am using 47nf cap parellel to a 4.7kohm resistor direct > > > from pin to pin. > > > > > Matt. > > > > > On Oct 28, 5:43 am, William <[email protected]> wrote: > > > > > > Hi Matt, > > > > > > Nice to hear from you! > > > > > > How about "sr23_" for prefix to the names? And I suppose you'll put > > > > the library under include/storage/sram/sr23k256.jal ? > > > > > > Take care: that is a lower-voltage part (not 5 volt tolerant), and > > > > you'll need a battery if you want persistent storage. Many picmicros > > > > will operate at lower voltages, but sometimes only at a reduced > > > > frequency. Also some older ICSP flash-burners will not work at the > > > > lower voltages. The ICD2 is fine, and I'm sure many others are also. > > > > > > William > > > > > > On Oct 28, 2:26 am, mattschinkel <[email protected]> wrote: > > > > > > > I am creating a lib for Microchip's 23k256 SRAM (costs about $1) > > > > > > > similar to 24LC256 EEPROM but much much faster (up to 20MHz) and > uses > > > > > SPI bus instead of I2C (spi mode_00) > > > > > > >http://www.microchip.com/wwwproducts/Devices.aspx?dDocName=en539039 > > > > > > > What should I name the variables & procedures since I cannot use > > > > > numbers as first characters in procedures & vars. > > > > > > > eg: > > > > > > > 23k256_init() is > > > > > > > const byte 23K256_READ = 0b_0000_0011 -- Read data from memory > > > > > array beginning at selected address > > > > > const byte 23K256_WRITE = 0b_0000_0010 -- Write data to memory > array > > > > > beginning at selected address > > > > > const byte 23K256_READ_STATUS = 0b_0000_0101 -- Read status > > > > > register > > > > > const byte 23K256_WRITE_SETTINGS = 0b_0000_0001 -- Write > settings > > > > > register > > > > > > > I'm an SPI kind of guy :o) > > > > > Matt.- Hide quoted text - > > > > > > - Show quoted text -- Hide quoted text - > > > > - Show quoted text - > > > --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "jallib" group. To post to this group, send email to [email protected] To unsubscribe from this group, send email to [email protected] For more options, visit this group at http://groups.google.com/group/jallib?hl=en -~----------~----~----~----~------~----~------~--~---
