Looking for simple way to interface BCD to serial (RS232)
in [Design]
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From: Joerg on 4 Jan 2010 19:13 JosephKK wrote: > On Sun, 27 Dec 2009 18:29:16 -0800, Joerg <invalid(a)invalid.invalid> wrote: > >> RFI-EMI-GUY wrote: >>> don wrote: >>>> RFI-EMI-GUY wrote: >>>>> I have a device that has a three digit LED display. The chip that >>>>> drives the LED also has four Binary Weighted outputs (1,2,4,8) and >>>>> three address pins for 100's, 10's and units. I want to drive a FIFO >>>>> UART of some sort to output an RS232 stream so that this device can >>>>> update a software program. Baud rate 300 to 4800 range would be nice >>>>> if possible. >>>>> >>>>> The updates are about 300/second >>>>> >>>>> Is there a real simple hardware FIFO UART that can do this without a >>>>> lot of extra hardware. I don't want a software fix unless I can do it >>>>> in PicAxe and can find code written. >>>>> >>>>> Off the shelf products OK I don't want to reinvent the wheel. >>>>> >>>> Do you docs on the outputs ? >>>> >>>> don >>> >>> I think you are asking the specs of the driving chip? Its an ICM7217IJI >>> Common Cathode 4 LED Display/Programmable Up/Down Counter. The BCD I/O >>> pins and the segment drivers b, d and f (d1, d2, d3) used to select >>> 100's. 10's and units (I may have order reversed). >>> >> That will not be so trivial because this is a chip that drives the LED >> in muxed fashion. > > Which immediatly leads to the next question, what is on the other side of that chip? An analog input signal :-) -- Regards, Joerg http://www.analogconsultants.com/ "gmail" domain blocked because of excessive spam. Use another domain or send PM.
From: JosephKK on 5 Jan 2010 01:09 On Sun, 03 Jan 2010 17:48:22 -0600, John Fields <jfields(a)austininstruments.com> wrote: >On Sat, 02 Jan 2010 13:33:49 -0800, "JosephKK"<quiettechblue(a)yahoo.com> >wrote: > >>On Sun, 27 Dec 2009 18:29:16 -0800, Joerg <invalid(a)invalid.invalid> wrote: >> >>>RFI-EMI-GUY wrote: >>>> don wrote: >>>>> RFI-EMI-GUY wrote: >>>>>> I have a device that has a three digit LED display. The chip that >>>>>> drives the LED also has four Binary Weighted outputs (1,2,4,8) and >>>>>> three address pins for 100's, 10's and units. I want to drive a FIFO >>>>>> UART of some sort to output an RS232 stream so that this device can >>>>>> update a software program. Baud rate 300 to 4800 range would be nice >>>>>> if possible. >>>>>> >>>>>> The updates are about 300/second >>>>>> >>>>>> Is there a real simple hardware FIFO UART that can do this without a >>>>>> lot of extra hardware. I don't want a software fix unless I can do it >>>>>> in PicAxe and can find code written. >>>>>> >>>>>> Off the shelf products OK I don't want to reinvent the wheel. >>>>>> >>>>> Do you docs on the outputs ? >>>>> >>>>> don >>>> >>>> >>>> I think you are asking the specs of the driving chip? Its an ICM7217IJI >>>> Common Cathode 4 LED Display/Programmable Up/Down Counter. The BCD I/O >>>> pins and the segment drivers b, d and f (d1, d2, d3) used to select >>>> 100's. 10's and units (I may have order reversed). >>>> >>> >>>That will not be so trivial because this is a chip that drives the LED >>>in muxed fashion. >> >>Which immediatly leads to the next question, what is on the other side of that chip? > >--- >If you're talking about the driven side of the 7217, it shouldn't make >much difference since all that's being output from the chip is four >parallel bits of BCD date along with four single-bit strobes with edges >that go low when the BCD data is valid. > >The job, therefore, is to assemble the four output data bits, the strobe >bit, the start and stop bits, and to send all of them as a 10 bit serial >word formatted as RS-232 TRANSMITTED DATA to a receiver somewhere which >is expecting it to come in at a particular bit rate. > >JF Already having the data in a convenient form reduces the design complexity.
From: JosephKK on 5 Jan 2010 01:12 On Mon, 04 Jan 2010 16:13:56 -0800, Joerg <invalid(a)invalid.invalid> wrote: >JosephKK wrote: >> On Sun, 27 Dec 2009 18:29:16 -0800, Joerg <invalid(a)invalid.invalid> wrote: >> >>> RFI-EMI-GUY wrote: >>>> don wrote: >>>>> RFI-EMI-GUY wrote: >>>>>> I have a device that has a three digit LED display. The chip that >>>>>> drives the LED also has four Binary Weighted outputs (1,2,4,8) and >>>>>> three address pins for 100's, 10's and units. I want to drive a FIFO >>>>>> UART of some sort to output an RS232 stream so that this device can >>>>>> update a software program. Baud rate 300 to 4800 range would be nice >>>>>> if possible. >>>>>> >>>>>> The updates are about 300/second >>>>>> >>>>>> Is there a real simple hardware FIFO UART that can do this without a >>>>>> lot of extra hardware. I don't want a software fix unless I can do it >>>>>> in PicAxe and can find code written. >>>>>> >>>>>> Off the shelf products OK I don't want to reinvent the wheel. >>>>>> >>>>> Do you docs on the outputs ? >>>>> >>>>> don >>>> >>>> I think you are asking the specs of the driving chip? Its an ICM7217IJI >>>> Common Cathode 4 LED Display/Programmable Up/Down Counter. The BCD I/O >>>> pins and the segment drivers b, d and f (d1, d2, d3) used to select >>>> 100's. 10's and units (I may have order reversed). >>>> >>> That will not be so trivial because this is a chip that drives the LED >>> in muxed fashion. >> >> Which immediatly leads to the next question, what is on the other side of that chip? > > >An analog input signal :-) And that would lead to an entirely different solution space.
From: John Fields on 5 Jan 2010 11:42 On Mon, 04 Jan 2010 22:12:14 -0800, "JosephKK"<quiettechblue(a)yahoo.com> wrote: >On Mon, 04 Jan 2010 16:13:56 -0800, Joerg <invalid(a)invalid.invalid> wrote: > >>JosephKK wrote: >>> On Sun, 27 Dec 2009 18:29:16 -0800, Joerg <invalid(a)invalid.invalid> wrote: >>> >>>> RFI-EMI-GUY wrote: >>>>> don wrote: >>>>>> RFI-EMI-GUY wrote: >>>>>>> I have a device that has a three digit LED display. The chip that >>>>>>> drives the LED also has four Binary Weighted outputs (1,2,4,8) and >>>>>>> three address pins for 100's, 10's and units. I want to drive a FIFO >>>>>>> UART of some sort to output an RS232 stream so that this device can >>>>>>> update a software program. Baud rate 300 to 4800 range would be nice >>>>>>> if possible. >>>>>>> >>>>>>> The updates are about 300/second >>>>>>> >>>>>>> Is there a real simple hardware FIFO UART that can do this without a >>>>>>> lot of extra hardware. I don't want a software fix unless I can do it >>>>>>> in PicAxe and can find code written. >>>>>>> >>>>>>> Off the shelf products OK I don't want to reinvent the wheel. >>>>>>> >>>>>> Do you docs on the outputs ? >>>>>> >>>>>> don >>>>> >>>>> I think you are asking the specs of the driving chip? Its an ICM7217IJI >>>>> Common Cathode 4 LED Display/Programmable Up/Down Counter. The BCD I/O >>>>> pins and the segment drivers b, d and f (d1, d2, d3) used to select >>>>> 100's. 10's and units (I may have order reversed). >>>>> >>>> That will not be so trivial because this is a chip that drives the LED >>>> in muxed fashion. >>> >>> Which immediatly leads to the next question, what is on the other side of that chip? >> >> >>An analog input signal :-) > >And that would lead to an entirely different solution space. --- "Solution space" ??? Pretentious nonsense. Regardless of what feeds the input(s) of the 7217, the outputs we're concerned with are the four-bit BCD I/O and the four digit strobes which identify which BCD digit is which. What the OP wants is a way to convert the BCD and digit strobe data into a format which can be read by an RS-232 DTE box, and several solutions were presented earlier on in the thread. JF
From: John Fields on 5 Jan 2010 11:48
On Mon, 04 Jan 2010 22:09:25 -0800, "JosephKK"<quiettechblue(a)yahoo.com> wrote: >On Sun, 03 Jan 2010 17:48:22 -0600, John Fields <jfields(a)austininstruments.com> wrote: > >>On Sat, 02 Jan 2010 13:33:49 -0800, "JosephKK"<quiettechblue(a)yahoo.com> >>wrote: >> >>>On Sun, 27 Dec 2009 18:29:16 -0800, Joerg <invalid(a)invalid.invalid> wrote: >>> >>>>RFI-EMI-GUY wrote: >>>>> don wrote: >>>>>> RFI-EMI-GUY wrote: >>>>>>> I have a device that has a three digit LED display. The chip that >>>>>>> drives the LED also has four Binary Weighted outputs (1,2,4,8) and >>>>>>> three address pins for 100's, 10's and units. I want to drive a FIFO >>>>>>> UART of some sort to output an RS232 stream so that this device can >>>>>>> update a software program. Baud rate 300 to 4800 range would be nice >>>>>>> if possible. >>>>>>> >>>>>>> The updates are about 300/second >>>>>>> >>>>>>> Is there a real simple hardware FIFO UART that can do this without a >>>>>>> lot of extra hardware. I don't want a software fix unless I can do it >>>>>>> in PicAxe and can find code written. >>>>>>> >>>>>>> Off the shelf products OK I don't want to reinvent the wheel. >>>>>>> >>>>>> Do you docs on the outputs ? >>>>>> >>>>>> don >>>>> >>>>> >>>>> I think you are asking the specs of the driving chip? Its an ICM7217IJI >>>>> Common Cathode 4 LED Display/Programmable Up/Down Counter. The BCD I/O >>>>> pins and the segment drivers b, d and f (d1, d2, d3) used to select >>>>> 100's. 10's and units (I may have order reversed). >>>>> >>>> >>>>That will not be so trivial because this is a chip that drives the LED >>>>in muxed fashion. >>> >>>Which immediatly leads to the next question, what is on the other side of that chip? >> >>--- >>If you're talking about the driven side of the 7217, it shouldn't make >>much difference since all that's being output from the chip is four >>parallel bits of BCD date along with four single-bit strobes with edges >>that go low when the BCD data is valid. >> >>The job, therefore, is to assemble the four output data bits, the strobe >>bit, the start and stop bits, and to send all of them as a 10 bit serial >>word formatted as RS-232 TRANSMITTED DATA to a receiver somewhere which >>is expecting it to come in at a particular bit rate. >> >>JF > >Already having the data in a convenient form reduces the design complexity. --- You do seem to have a remarkable grasp of the obvious but, other than demonstrating that, I don't understand what point you're trying to make. JF |