Thanks for the STM32 Blue Pill reference. An interesting looking board. On Tue, Nov 14, 2017 at 03:04:26PM +0000, Clint Jay wrote: > Jeff, you raise good points but I would prefer to be safe than sorry, > designing/building and coding for the MAX232 or other serial driver will > ensure compatibility (as far as RS-232 is able to be compatible) with the > widest range of PCs and prevent anything 'unpleasant' happening if the > device is plugged into an unknown machine. > > As heretical as it would seem I'd have to admit you may have a point abou= t > Arduino, it's a known hardware platform that is proven to work. > > Similarly, I've been exploring options with STM32 Blue Pill boards recent= ly > but I still like and write code for PIC devices, as and when I need extra > horsepower I may well leave the PIC Path and move to ARM, they're *so* > cheap and have an abundance of facilities. > > > > On 14 November 2017 at 14:54, Byron Jeff wrote: > > > Tony, > > > > There are actually two types of FTDI serial ports. There is the RS232 o= ne > > with a DB9 connector on the end. Typically that port will signal betwee= n > > +/- 7 volts or so. Then there are the small FTDI TTL serial adapters. > > Depending on configuration they will swing either between 0 and 5 volts= or > > 0 and 3.3 volts. > > > > In today's serial PC world rarely does an actual MAX232 need to be used= for > > level translation. Even with actual RS232 ports, virtually all of them > > signal properly with a 0/5V TTL signal. Note that the sign is inverted = such > > that a logical 1 is represented by 0V and a zero by 5V. > > > > For years I've used a simple voltage clamp to limit the swings. The bas= ic > > circuit is here: https://i.stack.imgur.com/jyZvD.gif D1 conducts when V= in > > is above VMax and D2 conducts then Vin is below Vmin. R limits the curr= ent. > > I typically put a second resistor after the clamp. I find that 1K for b= oth > > works well with PIC inputs. > > > > A couple of variations are helpful. If D1 and D2 are Schotty diodes the= n > > the voltage overshoot is typically only 0.3V or so. Also if D2 is a Zen= er > > then D1 is unnecessary because the Zener action will limit the high vol= tage > > while normal conduction clamps the low voltage. > > > > With the signal inverted there are a few things you can do to manage it= .. > > I've been using PIC24FV parts for several years. The hardware EUARTS on > > them can be inverted in software. It is also possible to bit bang a dig= ital > > input/output for serial. Otherwise a NPN transistor whose base is conne= cted > > to Vout, emitter grounded, and a pullup collector will invert the signa= l in > > hardware. > > > > Another thought that may be traitorous on this board: ever considered a= n > > Arduino? Complete boards with the USB serial adapter on board clock in = at > > about $5 USD. Boards like a Nano will plug right into a breadboard. Plu= g in > > a USB cable, load the Arduino IDE and you're going literally in about 5 > > minutes. Tons of libraries already built into the platform. > > > > As I've progressed in the hobby, I find that sometimes it's just more > > trouble than it's worth to try to roll everything from scratch. Back in= the > > PIC 16C54 days, the price and functionality was a compelling reason to > > switch as compared to the alternatives. But in 2017 with high level boa= rds > > such as a Raspberry PI Zero W that runs Linux and having a complete > > wireles setup > > for less than $10 USD and Arduino clones literally running 5 for $20, i= t > > becomes more difficult to justify wiring up a board from scratch and > > programming in assembly anymore. Those who have never done it may need = the > > experience. But those of us who have a closetfull of t-shirts with > > 'Assembly coder' emblazoned upon them? Not so much. I find now that I s= pend > > more time and energy trying to match the hardware/firmware to the > > application. It literally may be more adventageous to throw a RasPi Zer= oW > > into a problem to make a wireless remote light switch than any alternat= ive > > for > > example. > > > > BAJ > > > > On Wed, Nov 15, 2017 at 12:54:26AM +1100, Anthony Nixon wrote: > > > You wont need a level translator with the FTDI chip. It will directly > > > interface to the PIC, and the FTDI directly interfaces to the USB por= t > > > with the right support components which are just a handful of > > > passives. > > > > > > The trick is whether or not the FTDI will be powered by the USB port > > > or by the PIC circuit. > > > > > > cheers > > > > > > Tony > > > > > > On Tue, Nov 14, 2017 at 11:56 PM, Richard Pope > > wrote: > > > > Clint, > > > > I'll do that this evening after I get up. I appreciate the ins= ight > > > > and help! I will probably have to use a MAX232 to do the level > > > > translation. I appreciate you reminding me of that. > > > > Thanks, > > > > rich! > > > > > > > > On 11/14/2017 6:47 AM, Clint Jay wrote: > > > >> There may be, I've usually just rolled my own routines to service = the > > > >> EUSART though I haven't used the '4520 specifically. > > > >> > > > >> I don't think there are huge differences between most EUSART > > enabled mid > > > >> range devices so there should be plenty of example code to examine= and > > > >> modify for your needs. > > > >> > > > >> You'll need a level translator if you're going PIC to PC directly. > > > >> > > > >> On 14 Nov 2017 12:36, "Richard Pope" wrot= e: > > > >> > > > >>> Clint, > > > >>> Yes, I am using a FTDI to RS232 converter to hook the PC to= the > > > >>> PIC. I just found out that all that I need to do is treat the > > connection > > > >>> to the PIC as a Serial connection. Is there a MC Serial Library > > > >>> available? I'm the one that was confused. > > > >>> Thanks, > > > >>> rich! > > > >>> > > > >>> On 11/14/2017 6:28 AM, Clint Jay wrote: > > > >>>> I'm a little confused but the way I read your message would sugg= est > > that > > > >>>> you're going to connect your PIC to the PC with an FTDI USB to > > serial > > > >>>> device? > > > >>>> > > > >>>> Or have I misunderstood and you're hoping to connect the PIC to = the > > FTDI > > > >>>> with USB? > > > >>>> > > > >>>> On 14 Nov 2017 12:25, "Richard Pope" > > wrote: > > > >>>> > > > >>>> HELLO ALL, > > > >>>> . . . . I could really use some help with using USB on the PIC > > 18F4520. > > > >>>> I am going to use a FTDI USB to RS232 converter to talk to the P= IC > > > >>>> 18F4520 Through the RX and TX Pins. I want to send Configuration > > Code to > > > >>>> a 24C512 serial EPROM. When I add additional devices I want to b= e > > able > > > >>>> to update the EPROM. I also want to be able to use a Win 8.1 64b= it > > Pro > > > >>>> PC to control the Programmer. I also do a lot of searching and > > research > > > >>>> on materials that I acquire from the MicroChip website. I have b= een > > > >>>> reading the MC USB Device Firmware Framework User's Guide. > > > >>>> . . . . I have the latest version of MpLab, and the latest > > versions of > > > >>>> the X8, X18, and X32 Compilers installed. I also see that I need= to > > > >>>> install the latest versions of C30 C and C18 C Compilers and set= up > > the > > > >>>> proper Paths for these files. I don't mind doing the footwork. I= am > > > >>>> Disabled and retired. This gives me a lot of free time. > > > >>>> Thanks, > > > >>>> > > > >>>> Richard R. Pope > > > >>>> 1230 19th Street #5 > > > >>>> Reedsburg, WI 53959, USA > > > >>>> 1-608-768-7448 > > > >>>> mechanic_2@charter.net > > > >>>> > > > >>>> > > > >>>> --- > > > >>>> This email has been checked for viruses by Avast antivirus softw= are. > > > >>>> https://www.avast.com/antivirus > > > >>>> > > > >>>> -- > > > >>>> http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive > > > >>>> View/change your membership options at > > > >>>> http://mailman.mit.edu/mailman/listinfo/piclist > > > >>> -- > > > >>> http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive > > > >>> View/change your membership options at > > > >>> http://mailman.mit.edu/mailman/listinfo/piclist > > > >>> > > > > > > > > -- > > > > http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive > > > > View/change your membership options at > > > > http://mailman.mit.edu/mailman/listinfo/piclist > > > -- > > > http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive > > > View/change your membership options at > > > http://mailman.mit.edu/mailman/listinfo/piclist > > > > -- > > Byron A. Jeff > > Associate Professor: Department of Computer Science and Information > > Technology > > College of Information and Mathematical Sciences > > Clayton State University > > http://faculty.clayton.edu/bjeff > > -- > > http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive > > View/change your membership options at > > http://mailman.mit.edu/mailman/listinfo/piclist > > > > > > -- > Clint. > > *No trees were harmed in the sending of this mail. However, a large numbe= r > of electrons were greatly inconvenienced.* > -- > http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive > View/change your membership options at > http://mailman.mit.edu/mailman/listinfo/piclist -- James Cameron http://quozl.netrek.org/ -- http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .