Indeed, you are right. in the BBB I will test the concept with small frequency , like 4.5kS/s with 3.3MBit/S
2015-09-22 13:19 GMT-03:00 Julian David Rath <[email protected]>: > It will be impossible to do that with that amount of channels. Each > sample has 16 bit. > > 48 Channels * 450 kS/s * 16 bit = 345.6 Mbit/S. > > Besides that is probably beyond any bus speed on the SoC. It would as > well require you to interface with 24 SPI lines in parallel in full > speed. There is absolutely no way to do that on a BeagleBone. You'll > have to go for a FPGA or a faster ADC with analog multiplexing in you > front-end. > > Bests, > > Julian > > > > > > On Tue, Sep 22, 2015 at 6:10 PM, Antônio Albuquerque <[email protected]> > wrote: > > something around 450kS/s > > > > > > 2015-09-22 12:47 GMT-03:00 Julian David Rath <[email protected]>: > >> > >> What is your planned sample frequency? > >> > >> On Tue, Sep 22, 2015 at 4:50 PM, Antônio Albuquerque <[email protected]> > >> wrote: > >> > Hello Julian > >> > > >> > Thank you for your fast reply. > >> > I am trying to use the same ADS8528 to read 48 channel of sensors > using > >> > daisy-chain to get the information simultaneously. > >> > Definitely I appreciate if you can send me some code. > >> > > >> > Best regards, > >> > Antonio > >> > > >> > > >> > 2015-09-22 10:48 GMT-03:00 Julian David Rath <[email protected]>: > >> >> > >> >> Hej Antonio, > >> >> > >> >> I used the PRU to communicate with the BBB, which works quite good. > >> >> But datarates with more the 20 Mbit are not realistic since the PRUs > >> >> have a clock of 200 Mhz. > >> >> If you are interested I could prepare some code to release. > >> >> > >> >> bests, > >> >> > >> >> Julian > >> >> > >> >> > >> >> On Tue, Sep 22, 2015 at 2:52 AM, <[email protected]> wrote: > >> >> > Hello Julian, > >> >> > I am having the same issue, could you let me know about the > solution? > >> >> > Have > >> >> > you found some workaround to use BBB->SPI and ADS8528? > >> >> > Best regards > >> >> > Antonio > >> >> > > >> >> > > >> >> > Em segunda-feira, 10 de março de 2014 07:15:25 UTC-3, Julian David > >> >> > Rath > >> >> > escreveu: > >> >> >> > >> >> >> Hi, > >> >> >> > >> >> >> I just found out that this is a better place to ask my question, > it > >> >> >> seams > >> >> >> like there is also a beaglebone Google group, little confusing. So > >> >> >> here > >> >> >> my > >> >> >> cross-post: > >> >> >> > >> >> >> I'd like to connect 4 ADS8528[0] daisy-chained via SPI to a BBB. I > >> >> >> want > >> >> >> to > >> >> >> test it in different iterations first I want to measure the 32 > >> >> >> Analog > >> >> >> input > >> >> >> channels captured by the ADS8528s with 1kHz and at the end with > >> >> >> 200kHz. > >> >> >> Those ADS8528 using 4 SPI Channels in daisy-chain mode. So I did > >> >> >> some > >> >> >> calculations on the needed bandwidth: > >> >> >> > >> >> >> for 1Khz: > >> >> >> 12Bit * 32Channels * 4KHz = 384 Kbit/s > >> >> >> > >> >> >> On 4 SPI Channels that means: > >> >> >> 12* 32*1Khz = 96 Kbit/s per SPI channel > >> >> >> > >> >> >> for 200Khz: > >> >> >> 12Bit * 32Channels * 200KHz = 76.8 Mbit/s = 9.6MByte/s > >> >> >> > >> >> >> On 4 SPI Channels that means: > >> >> >> 76.8Mb/s /4 = 19.2 Mbit/s per SPI channel > >> >> >> > >> >> >> Now 2 things: > >> >> >> * Should/Can I use the built-in SPI of the BBB or do I have to > >> >> >> implement > >> >> >> 4 channels SPI bus by hand (High datarates PRUSS I guess)? > >> >> >> * Do you think the high datarates for the 200Khz are achievable? > >> >> >> > >> >> >> Thanks, > >> >> >> > >> >> >> /Julian > >> >> >> > >> >> >> [0]: http://www.ti.com/product/ads8528 > >> >> > > >> >> > -- > >> >> > For more options, visit http://beagleboard.org/discuss > >> >> > --- > >> >> > You received this message because you are subscribed to a topic in > >> >> > the > >> >> > Google Groups "BeagleBoard" group. > >> >> > To unsubscribe from this topic, visit > >> >> > > >> >> > > https://groups.google.com/d/topic/beagleboard/SpRz6u9_8aA/unsubscribe. > >> >> > To unsubscribe from this group and all its topics, send an email to > >> >> > [email protected]. > >> >> > For more options, visit https://groups.google.com/d/optout. > >> >> > >> >> -- > >> >> For more options, visit http://beagleboard.org/discuss > >> >> --- > >> >> You received this message because you are subscribed to a topic in > the > >> >> Google Groups "BeagleBoard" group. > >> >> To unsubscribe from this topic, visit > >> >> > https://groups.google.com/d/topic/beagleboard/SpRz6u9_8aA/unsubscribe. > >> >> To unsubscribe from this group and all its topics, send an email to > >> >> [email protected]. > >> >> For more options, visit https://groups.google.com/d/optout. > >> > > >> > > >> > > >> > > >> > -- > >> > Atenciosamente, > >> > Antônio Albuquerque > >> > > >> > -- > >> > For more options, visit http://beagleboard.org/discuss > >> > --- > >> > You received this message because you are subscribed to a topic in the > >> > Google Groups "BeagleBoard" group. > >> > To unsubscribe from this topic, visit > >> > https://groups.google.com/d/topic/beagleboard/SpRz6u9_8aA/unsubscribe > . > >> > To unsubscribe from this group and all its topics, send an email to > >> > [email protected]. > >> > For more options, visit https://groups.google.com/d/optout. > >> > >> -- > >> For more options, visit http://beagleboard.org/discuss > >> --- > >> You received this message because you are subscribed to a topic in the > >> Google Groups "BeagleBoard" group. > >> To unsubscribe from this topic, visit > >> https://groups.google.com/d/topic/beagleboard/SpRz6u9_8aA/unsubscribe. > >> To unsubscribe from this group and all its topics, send an email to > >> [email protected]. > >> For more options, visit https://groups.google.com/d/optout. > > > > > > > > > > -- > > Atenciosamente, > > Antônio Albuquerque > -- Atenciosamente, Antônio Albuquerque -- For more options, visit http://beagleboard.org/discuss --- You received this message because you are subscribed to the Google Groups "BeagleBoard" group. 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