From: Julian David Rath <[email protected]> Reply-To: <[email protected]> Date: Monday, March 10, 2014 at 2:15 AM To: <[email protected]> Subject: [beagleboard] 4 Channel SPI
> 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? While SPI can achieve the bandwidth you require, I¹m not sure you will get this to work without a kernel driver given that the message transfers are small so DMA won¹t be used. You may want to ask this question on the Linux-IIO forum. Regards, John > > 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 the Google Groups > "BeagleBoard" group. > To unsubscribe from this group and stop receiving emails from it, 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 the Google Groups "BeagleBoard" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. For more options, visit https://groups.google.com/d/optout.
