(Skip intro to next paragraph if you want) I am a veteran Windows programmer who is just getting into microcontroller programming. As my first post here, I want to congratulate Paul S. on your excellent product, your unabated development, and your honorable commitment to customer support. As the developer of a Windows software product with its own community, I am sympathetic to everything Teensy. I know what it's like to make a quality product that is a not the cheapest solution, but is the average consumer's best option. For me, when I saw that the Teensy Board could be compiled easily at low frequency, had a wealth of tested libraries, and especially when I saw 1) TeensyThreads and that 2) Paul ported FreqMeasure to the FreqMeasureMulti version - it became clear that Teensy was the best choice for my project. I am terribly excited about these boards and plan to NEVER go back to Adafruit!
If it weren't for TeensyThreads and FreqMeasureMulti, I wouldn't be here. Never doubt that the incredible software development behind Teensy drives sales. I was indescribably excited when I found this hardware and software combo would solve my real-time pulse SD logger latency problems I'd been having on Adafruit boards, not using an RTOS.
Back-on-topic question: I notice a non-linear, extreme savings in power when going from 4MHz to 2MHz. After some digging, I noticed it is because of "VLPR" which is activated in the Teensy code at 2MHz.
According to spec here: http://cache.freescale.com/files/32bit/doc/app_note/AN4503.pdf
...You should be able to activate this mode in 4MHz. But alas: it appears Paul's low-level bootloader code is already writing the "SMC_PMPROT" bit which is write-once-only. This would explain why my attempts to mess with the low-level registers on Teensy 3.6 @ 4MHz to activate VLPR have failed.
Plugged into USB 5V I get 0.006A/6mA running at 4MHz, and 0.000A (my USB display can't even show the actual consumption, it's so low!) at 2MHz.
I have profiled my application, and I need to be able to SD card write 1300 pulses/second (6 bytes of info each) without dropping any pulses. The TeensyThreads+SDFatSDIO combo has been amazing and I am extremely content with my purchase (I did fry/totally destroy my first Teensy 3.6 while wiring on breadboard, but good thing I bought 2, and I bought a third afterwards).
However, the 2MHz/4MHz boundary seems to be the threshold between not good enough/good enough for my 1300 pulses * 6 bytes / second requirement, without dropping any pulses (mandatory).
For this reason, I would love to have the power savings of VLPR @ 4MHz, and the only thing holding me back could be just a few lines of code in Paul's bootloader.
1. Is it possible do to without a Teensy software update?
2. If so, can someone post code for enabling VLPR @ 4MHz on Teensy 3.6?
Many thanks in advance from an enthusiastic new customer.
If it weren't for TeensyThreads and FreqMeasureMulti, I wouldn't be here. Never doubt that the incredible software development behind Teensy drives sales. I was indescribably excited when I found this hardware and software combo would solve my real-time pulse SD logger latency problems I'd been having on Adafruit boards, not using an RTOS.
Back-on-topic question: I notice a non-linear, extreme savings in power when going from 4MHz to 2MHz. After some digging, I noticed it is because of "VLPR" which is activated in the Teensy code at 2MHz.
According to spec here: http://cache.freescale.com/files/32bit/doc/app_note/AN4503.pdf
...You should be able to activate this mode in 4MHz. But alas: it appears Paul's low-level bootloader code is already writing the "SMC_PMPROT" bit which is write-once-only. This would explain why my attempts to mess with the low-level registers on Teensy 3.6 @ 4MHz to activate VLPR have failed.
Plugged into USB 5V I get 0.006A/6mA running at 4MHz, and 0.000A (my USB display can't even show the actual consumption, it's so low!) at 2MHz.
I have profiled my application, and I need to be able to SD card write 1300 pulses/second (6 bytes of info each) without dropping any pulses. The TeensyThreads+SDFatSDIO combo has been amazing and I am extremely content with my purchase (I did fry/totally destroy my first Teensy 3.6 while wiring on breadboard, but good thing I bought 2, and I bought a third afterwards).
However, the 2MHz/4MHz boundary seems to be the threshold between not good enough/good enough for my 1300 pulses * 6 bytes / second requirement, without dropping any pulses (mandatory).
For this reason, I would love to have the power savings of VLPR @ 4MHz, and the only thing holding me back could be just a few lines of code in Paul's bootloader.
1. Is it possible do to without a Teensy software update?
2. If so, can someone post code for enabling VLPR @ 4MHz on Teensy 3.6?
Many thanks in advance from an enthusiastic new customer.