Looking for simple way to interface BCD to serial (RS232)
in [Design]
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From: RFI-EMI-GUY on 27 Dec 2009 16:52 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. -- Joe Leikhim K4SAT "The RFI-EMI-GUY"� "Use only Genuine Interocitor Parts" Tom Servo ;-P
From: don on 27 Dec 2009 17:29 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
From: John Fields on 27 Dec 2009 18:21 On Sun, 27 Dec 2009 16:52:22 -0500, RFI-EMI-GUY <Rhyolite(a)NETTALLY.COM> 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. --- The way I'd do it would be to broadside load a 10 bit parallel-in serial-out shift registers with the BCD data, the digit data, a stop and a start bit, and then shift the data out serially to the RS-232 input of whatever's updating your software program. If the broadside data into the shifter is updating at about 300Hz, that's about 3.33ms, so to shift it all out before the next update comes along would require a bit clock at least 10 times faster than that, or about 333�s/3.3kHz. Duck soup, maybe. ;) What's the chip that's driving the display? JF
From: RFI-EMI-GUY on 27 Dec 2009 21:19 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). -- Joe Leikhim K4SAT "The RFI-EMI-GUY"� "Use only Genuine Interocitor Parts" Tom Servo ;-P
From: RFI-EMI-GUY on 27 Dec 2009 21:20
John Fields wrote: > On Sun, 27 Dec 2009 16:52:22 -0500, RFI-EMI-GUY <Rhyolite(a)NETTALLY.COM> > 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. > > --- > The way I'd do it would be to broadside load a 10 bit parallel-in > serial-out shift registers with the BCD data, the digit data, a stop and > a start bit, and then shift the data out serially to the RS-232 input of > whatever's updating your software program. > > If the broadside data into the shifter is updating at about 300Hz, > that's about 3.33ms, so to shift it all out before the next update comes > along would require a bit clock at least 10 times faster than that, or > about 333�s/3.3kHz. > > Duck soup, maybe. ;) > > What's the chip that's driving the display? > > JF 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). -- Joe Leikhim K4SAT "The RFI-EMI-GUY"� "Use only Genuine Interocitor Parts" Tom Servo ;-P |