LeafLabs Garden » Topic: One way to generate high speed signal

LeafLabs Garden » Topic: One way to generate high speed signal http://forums.leaflabs.com/topic.php?id=1055 A place to share, learn, and grow... en-US Fri, 22 Jan 2016 00:24:15 +0000 http://bbpress.org/?v=1.0.2 <![CDATA[Search]]> q http://forums.leaflabs.com/search.php gbulmer on "One way to generate high speed signal" http://forums.leaflabs.com/topic.php?id=1055#post-6480 Wed, 21 Sep 2011 08:53:05 +0000 gbulmer 6480@http://forums.leaflabs.com/ gulu2065 - that should work. Did you check the correct pins? <a href="http://leaflabs.com/docs/hardware/maple.html#master-pin-map" rel="nofollow">http://leaflabs.com/docs/hardware/maple.html#master-pin-map</a> PB5 is pin D4 and PB6 is pin D5 Did you set the pinMode for those pins? <pre><code>pinMode(D4, OUTPUT); pinMode(D5, OUTPUT);</code></pre> It might be easier to work backwards, and use the pin map to figure out which pins you want to check. (full disclosure: I am not a member of LeafLabs staff) gulu2065 on "One way to generate high speed signal" http://forums.leaflabs.com/topic.php?id=1055#post-6468 Wed, 21 Sep 2011 01:41:15 +0000 gulu2065 6468@http://forums.leaflabs.com/ mbolivar, are you sure this will work? I tried but it do not set them both. Only set one. Could you explain it in more detail? Thanks, mbolivar on "One way to generate high speed signal" http://forums.leaflabs.com/topic.php?id=1055#post-6460 Tue, 20 Sep 2011 21:22:26 +0000 mbolivar 6460@http://forums.leaflabs.com/ gbulmer, Thanks for the links. I've added a link to thread with id=895 to the FAQ entry: <a href="https://github.com/leaflabs/leaflabs-docs/commit/dc70ddaad588c23525c3e8ff4ba080e0ac313719" rel="nofollow">https://github.com/leaflabs/leaflabs-docs/commit/dc70ddaad588c23525c3e8ff4ba080e0ac313719</a> (A link to the thread with id=774 is already present). gbulmer on "One way to generate high speed signal" http://forums.leaflabs.com/topic.php?id=1055#post-6454 Tue, 20 Sep 2011 20:37:23 +0000 gbulmer 6454@http://forums.leaflabs.com/ You might find these threads useful too: <a href="http://forums.leaflabs.com/topic.php?id=774" rel="nofollow">http://forums.leaflabs.com/topic.php?id=774</a> <a href="http://forums.leaflabs.com/topic.php?id=895" rel="nofollow">http://forums.leaflabs.com/topic.php?id=895</a> (and the threads it references) mbolivar on "One way to generate high speed signal" http://forums.leaflabs.com/topic.php?id=1055#post-6451 Tue, 20 Sep 2011 18:17:07 +0000 mbolivar 6451@http://forums.leaflabs.com/ Do you really want to say several ports? You can't write to pins on different ports (like GPIOA and GPIOB) with the same instruction. If what you mean is several bits, then you can just pick two pins on the same port using your board's <a href="http://leaflabs.com/docs/gpio.html#pin-maps">pin map</a>, and use the bit set/reset register, BSRR, to set or clear both bits at the same time. See ST RM0008 <a href="http://leaflabs.com/docs/gpio.html#recommended-reading">(linked to here)</a> for more information. Edit: for example, you could say <code>GPIOB_BASE->BSRR = BIT(6) | BIT(5);</code> to set both bit 6 and 5 (on GPIOB) at the same time. To clear them at the same time, you could use <code>GPIOB_BASE->BSRR = BIT(6 + 16) | BIT(5 + 16);</code> gulu2065 on "One way to generate high speed signal" http://forums.leaflabs.com/topic.php?id=1055#post-6450 Tue, 20 Sep 2011 17:39:46 +0000 gulu2065 6450@http://forums.leaflabs.com/ mbolivar, this is great, In fact I just reading something like this. Now I am interesting in how to write several port at the same time, i.e. let them work at the same speed and thus generate abitrary bits I want. Do you have any idea about it? mbolivar on "One way to generate high speed signal" http://forums.leaflabs.com/topic.php?id=1055#post-6449 Tue, 20 Sep 2011 17:34:23 +0000 mbolivar 6449@http://forums.leaflabs.com/ gulu2065, you may find this FAQ interesting: <a href="http://leaflabs.com/docs/faq.html#how-do-i-write-to-a-pin-at-high-speed" rel="nofollow">http://leaflabs.com/docs/faq.html#how-do-i-write-to-a-pin-at-high-speed</a> gulu2065 on "One way to generate high speed signal" http://forums.leaflabs.com/topic.php?id=1055#post-6442 Tue, 20 Sep 2011 16:12:27 +0000 gulu2065 6442@http://forums.leaflabs.com/ Yesterday I found one interesting (For a green hand, I think so,) way to generate high frequency signal. I post here, hope it will help anyone needed #define PIN_B6_HIGH (GPIOB_BASE)->BSRR = BIT(6) #define PIN_B6_LOW (GPIOB_BASE)->BRR = BIT(6) void setup() { pinMode(5, OUTPUT); // B6 is pin 5 } void loop() { myloop: PIN_B6_HIGH; PIN_B6_LOW; goto myloop; } If you want to moderate frequency or duty, you could use this delay __asm__("nop\n\t"); it could offer a 30ns? I forget exact number but much shorter than the delayMicrosenonds();