http://forums.leaflabs.com/topic.php?id=11851 A place to share, learn, and grow... en-US Fri, 22 Jan 2016 00:20:47 +0000 http://bbpress.org/?v=1.0.2 q http://forums.leaflabs.com/search.php http://forums.leaflabs.com/topic.php?id=11851#post-26345 Fri, 31 May 2013 10:26:20 +0000 gbulmer 26345@http://forums.leaflabs.com/ <p>stafil - The STM32F103 in Maple and Maple-mini only support 8 or 16 bit SPI transfers. So you could try the hardware route and get a board with a newer MCU, like an STM32F3, STM32F4, STM32F05, for example on one of ST's Discovery boards.</p> <p>Or you could do it by 'bit-banging', which is changing the state of output pins in software.<br /> Very helpfully, tlgosser has posted a link to code which does this on the thread <a href="http://forums.leaflabs.com/topic.php?id=11844" rel="nofollow">http://forums.leaflabs.com/topic.php?id=11844</a><br /> So you could try reading that, and come back with questions.</p> <p>How fast does the transfer need to happen? A carefully written software approach will run at a few megabits/second. So software SPI might be too slow.<br /> Does the program need to do anything else? If it has to do a lot of other processing at the same time, software SPI might take too much processor time.</p> <p>In either case, you could 'make' you're own SPI. SPI is just a shift register, which are typically under $0.50, and with care two can be 'stacked' to make 9 bits. It could be loaded 9 bits at a time, or less bits if the MCU is short of pins. You'll look for Parallel In Serial Out (PISO) shift registers, for example 74HC165 (<a href="http://uk.rs-online.com/web/p/counters-shift-registers/1697453/" rel="nofollow">http://uk.rs-online.com/web/p/counters-shift-registers/1697453/</a>)</p> <p>The other SPI signal is a 'clock', which is a continuous square wave which runs will data is being moved. This would be generated by a timer output compare (PWM) pin. </p> http://forums.leaflabs.com/topic.php?id=11851#post-26325 Fri, 31 May 2013 01:47:43 +0000 stafil 26325@http://forums.leaflabs.com/ <p>Hi all,</p> <p>pls help me, how i programmed 9bit spi?</p> <p>Thx </p>