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greetings all.. Anyone got good experience with serial data transfer??? can u send me some code? specially for transfer using autobuffering.. and alternate framing.. i intend to implement a PLL using a dedicated PLL chip.. and
control it using 2181. The chip accepts data as 21bits.. serially.. I am open to an alternative solution..
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ADSP-2181 - the problem still persists..
Started by ●June 18, 2002
Reply by ●June 18, 20022002-06-18
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>From: manish marwaha <> >To: >Subject: [adsp] ADSP-2181 - the problem still persists.. >Date: Mon, 17 Jun 2002 21:19:54 -0700 (PDT) >greetings all.. > >Anyone got good experience with serial data transfer??? can u send me some >code? specially for transfer using autobuffering.. > >and alternate framing.. > >i intend to implement a PLL using a dedicated PLL chip.. and control it >using 2181. The chip accepts data as 21bits.. serially.. > >but adsp can send data only as word lengths of 3-16.. You could just toggle a couple of flag outputs, and 'bit-bang' the data. I've done this to configure an FPGA with a clocked serial bit stream. Leon -- Leon Heller, G1HSM Tel: +44 1327 359058 Email: My web page: http://www.geocities.com/leon_heller My low-cost Altera Flex design kit: http://www.leonheller.com |
Reply by ●June 18, 20022002-06-18
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Manish- You are making this too hard. Just use GPIO lines for clock and data and control the lines using single instructions to set/reset the line. I.e. like: for (i=0; i<21; i++) { set clock high set data line = bits[i] set clock low /* latch data into PLL chip */ delay(as needed) } The PLL chip doesn't care about speed, frame sync, space between bits, etc. How often will you program the PLL chip? Not very often, so why use up a valuable serial port for this peripheral? Jeff Brower DSP sw/hw engineer Signalogic manish marwaha wrote: > > greetings all.. > > Anyone got good experience with serial data transfer??? can u send me some code? > specially for transfer using autobuffering.. > > and alternate framing.. > > i intend to implement a PLL using a dedicated PLL chip.. and control it using > 2181. The chip accepts data as 21bits.. serially.. > > but adsp can send data only as word lengths of 3-16.. > > one solution that i have come up with is to use 2181 with a 7-bit word length and > transmit 3 such words. (i am thinking on the lines of autobuffering) > > I am open to an alternative solution.. > > regards > manish |
Reply by ●June 18, 20022002-06-18
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Like the others said, you don't need to use up a serial port just because the PLL chip accepts serial data. Just use 3 GPIO lines for clk, data and CS/LD as the 3rd line (you can use a 4th one but most chips needs only 3). Take your 21 bit data, write a for loop to extract each bit from your 21 bit data, and set the data line either high or low appropriately. of course you need to pulse the clock line each time. At the end of the 21 bit transmission, you probably need to pulse the LD line or you may need to keep the CS line low during your transmission (depends on the timing diagram of your PLL data sheet). Cheers Bhaskar --- In adsp@y..., manish marwaha <manish_marwaha@y...> wrote: > > greetings all.. > > Anyone got good experience with serial data transfer??? can u send me some code? specially for transfer using autobuffering.. > > and alternate framing.. > > i intend to implement a PLL using a dedicated PLL chip.. and control it using 2181. The chip accepts data as 21bits.. serially.. > > but adsp can send data only as word lengths of 3-16.. > > one solution that i have come up with is to use 2181 with a 7-bit word length and transmit 3 such words. (i am thinking on the lines of autobuffering) > > I am open to an alternative solution.. > > regards > manish > > > --------------------------------- > |
Reply by ●June 18, 20022002-06-18
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At 11:19 PM 6/17/2002, manish marwaha wrote: >greetings all.. > >Anyone got good experience with serial data transfer??? can u send me some >code? specially for transfer using autobuffering.. > >and alternate framing.. > >i intend to implement a PLL using a dedicated PLL chip.. and control it >using 2181. The chip accepts data as 21bits.. serially.. > >but adsp can send data only as word lengths of 3-16.. > >one solution that i have come up with is to use 2181 with a 7-bit word >length and transmit 3 such words. (i am thinking on the lines of autobuffering) > >I am open to an alternative solution.. > >regards >manish First, I would use a newer 218x part (100 pin package)., such as the 2186M or 2185M. The 2181 is really only used for existing designs. I think you want to use Sport 0 in TDM mode. This is usually the easiest way to create these kind of interfaces. You may need to take a close look at the frame sync line. I assume you have the ADI book: ADSP-2100 Family Users Manual. When I write software for these kind of applications, I usually use a logic analyzer or a DSO to monitor the Sport Lines since it is very easy to get something wrong. You might want to look at some of the codec interfacing examples on the ADI web site since the basic technique is the same. Al Clark Danville Signal Processing, Inc. -------------------------------- Purveyors of Fine DSP Hardware and other Cool Stuff Available at http://www.danvillesignal.com |
