Post by thread:[PIC]:BAR GRAPH

Hi list ... Hopefully someone will be able to help me out here, I am controlling the speed of a remote DC motor using a simple Hex switch. ( 16 discrete speed steps ( PWM )) I could have used either an ADC or rotary encoder to get finer resolution, but in this application it is not necessary, in fact on or off would be just fine. I also happen to have a 1 line 16 character lcd and thought it would be nice to show the speed as a bargraph ? My problem, is that I cannot think how to get started - I have had success in the past with CGram so I was thinking maybe increment a register and light a segment on the lcd per speed step, unfortunately I now have a mental block as to actually implement this. So, if someone could outline the steps that would be needed that would be great .. Thanks Steve ********************************************************************** Information in this email is confidential and may be privileged. It is intended for the addressee only. If you have received it in error, please notify the sender immediately and delete it from your system. You should not otherwise copy it, retransmit it or use or disclose its contents to anyone. Thank you for your co-operation. ********************************************************************** -- http://www.piclist.com#nomail Going offline? Don't AutoReply us! email spam_OUTlistservTakeThisOuTmitvma.mit.edu with SET PICList DIGEST in the body

Goring, Steve wrote: > ********************************************************************** > Information in this email is confidential and may be privileged. > It is intended for the addressee only. If you have received > it in error, > please notify the sender immediately and delete it from your system. > You should not otherwise copy it, retransmit it or use or disclose its > contents to anyone. > Thank you for your co-operation. > ********************************************************************** .....PICLISTKILLspam@spam@MITVMA.MIT.EDU retransmitted this email and disclosed its contents to all members. Google did even more. Hey folks, I wouldn't like feeling I'm a sort of spy or something. Mike. -- http://www.piclist.com#nomail Going offline? Don't AutoReply us! email listservKILLspammitvma.mit.edu with SET PICList DIGEST in the body

> thought it would be nice to show > the speed as a bargraph ? > > My problem, is that I cannot think how to get started Hello, I have done this for a Volume display on my car MP3 player. I shall assume thet you know how to control the disply and write characters to it. 1) Define some special characters. These will go in the User Defined ares of the LCD module, and can be used by sending the appropriate character code. The characters should represent 1 and 2 vertical bars. Each character cell on the LCD is 5 pixels wide, and each cell is seperated from its neighbour by a 1 pixel gap. If you define a character that is like this: 00011 00011 00011 00011 00011 00011 00011 or this 11000 11000 11000 11000 11000 11000 11000 (depending on which way your bargraph goes) and this 11011 11011 11011 11011 11011 11011 11011 then you can represent 1/2 cell steps in your bargraph. Alternatively you can define a solid block and just have whole cell steps. 2) Think about how you will map your speed to the bargraph. You have 16 character cells. If they are all full then you will be representing full speed, or 100%. If they are all blank you will be representing 0%. Each cell represents 6.25% when full, or 3.125% when half full, unless you put characters like 0 and 100 at either end. 3) Figure out the maths so that when you have a number which is to be displayed on the bargraph you calculate how many full cell characters you need, and whether the last one is a half cell or blank. 4) Send the appropriate characters to the screen. Does this help? Andy -- http://www.piclist.com#nomail Going offline? Don't AutoReply us! email .....listservKILLspam.....mitvma.mit.edu with SET PICList DIGEST in the body

Sorry, forgot to add, if the value you are displaying is a byte value (or general power of 2) then that makes the maths very easy, and you know, it would really help me if I actually read what you wrote (which I just did, halfway through that sentence). The maths for your project are *very* easy, and you don't need 1/2 cell characters. <flustered>Of course, I knew that, and I was um, merely expanding on the problem in case, er, others wanted to do a similar thing</flustered> Andy -- http://www.piclist.com#nomail Going offline? Don't AutoReply us! email EraseMElistservspam_OUTTakeThisOuTmitvma.mit.edu with SET PICList DIGEST in the body

{Quote hidden}> -----Original Message----- > From: Goring, Steve [SMTP:Steve.Goringspam_OUTBSKYB.COM] > Sent: Thursday, July 04, 2002 6:01 AM > To: @spam@PICLISTKILLspamMITVMA.MIT.EDU > Subject: [PIC]:BAR GRAPH > > Hi list ... > > Hopefully someone will be able to help me out here, I am controlling the > speed of a > remote DC motor using a simple Hex switch. ( 16 discrete speed steps ( PWM > )) > > I could have used either an ADC or rotary encoder to get finer resolution, > but in this > application it is not necessary, in fact on or off would be just fine. > > I also happen to have a 1 line 16 character lcd and thought it would be > nice > to show > the speed as a bargraph ? > > My problem, is that I cannot think how to get started - I have had success > in the > past with CGram so I was thinking maybe increment a register and light a > segment > on the lcd per speed step, unfortunately I now have a mental block as to > actually > implement this. > > So, if someone could outline the steps that would be needed that would be > great .. > > Thanks > > Steve > I think a solid block is already defined in the LCD character set so you wouldn't even need to generate your own as you don't need any better resolution than one character block. The easiest way is to simply send the clear/home command to the lcd, and then write as many blocks as the value of you PWM count e.g. (sorry it's in (pseudo) C) void UpdateBargraph(char count) // count holds PWM value 0 -15 { char i; if(count > 15) // clamp number of chars to send count = 15; lcd_clear(); // send command 0x01 to LCD (clear and home) for(i=0;i<=count;i++) lcd_write(0xFF); // write solid block character } The only downside with this is that it may cause flicker if the display is updated very often. To avoid this would need some cunning and some more code to only write the characters that are needed to make the bar shorter or longer void UpdateBargraph(char count) { static prvcount; char i; if(count > 15) // clamp number of chars to send count = 15; if (count < prvcount) // bar graph needs to be shorter { lcd_goto(count + 1); // move cursor to first blank character for(i=0 ;i < (prvcount - count); i++) lcd_putch(' '); // write spaces to the ends of the display } else if (count > prvcount) // bar graph needs to be longer { lcd_goto(prvcount + 1); // move cursor to first blank character for(i=0; i < (count - prvcount); i++) lcd_putch(0xFF); // write solid blocks } prvcount = count; // store current bar value for next update } I presume you already have some code to control the LCD? If not then there are dozens of examples on the net for PIC code. The above should be pretty trivial to convert to assembler if that's what you are using. Regards Mike -- http://www.piclist.com#nomail Going offline? Don't AutoReply us! email KILLspamlistservKILLspammitvma.mit.edu with SET PICList DIGEST in the body

Thanks to all those that replied ... Steve ********************************************************************** Information in this email is confidential and may be privileged. It is intended for the addressee only. If you have received it in error, please notify the sender immediately and delete it from your system. You should not otherwise copy it, retransmit it or use or disclose its contents to anyone. Thank you for your co-operation. ********************************************************************** -- http://www.piclist.com#nomail Going offline? Don't AutoReply us! email RemoveMElistservTakeThisOuTmitvma.mit.edu with SET PICList DIGEST in the body

Hi Andy ... Just got back to work today and am pleased to report that I do indeeed have a speed bargraph ... The theory of your code worked for me although I have implemented it slightly differently due to the fact that I do have physically a single row of 16 characters but which are in fact two lines of 8 next to each other. So thanks again .... Steve ********************************************************************** Information in this email is confidential and may be privileged. It is intended for the addressee only. If you have received it in error, please notify the sender immediately and delete it from your system. You should not otherwise copy it, retransmit it or use or disclose its contents to anyone. Thank you for your co-operation. ********************************************************************** -- http://www.piclist.com hint: PICList Posts must start with ONE topic: [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads