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jpnorair

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Everything posted by jpnorair

  1. Basically, I'm looking at the FormLabs Form 1+. http://formlabs.com/products/form-1-plus/ Anything under about $4000 is being considered. One of the main things I need to do is print elastomers (rubbery compounds). The other main thing I need to do is print small parts with a variety of plastics, as part of antenna prototyping. Obviously, the antennas will be metal, but I can print plastic spacers, jigs, cores, etc, using all kinds of different plastics with different dielectric properties. This excites me . I'm just fishing to see if anyone has good recommendations. Thanks!
  2. My MSP432 launchpad is ordered ... A STM32L4 Eval kit is also on the way. Yes, there will be a shootout on my blog sometime in the next couple months. It will take a little bit of time to do, though, because I intend on being thorough, and not only addressing benchmarks but also practical concerns for embedded engineers (especially for IoT apps). Here is the STM32L4: no surprise that it's very similar to the MSP432. http://www.st.com/web/en/catalog/mmc/FM141/SC1169/SS1580?s_searchtype=keyword
  3. Thanks for the advice. Right now, I still have no CC1310 hardware, so I'm just brainstorming. One great announcement for me is Energia MT. It runs as threads on TI-RTOS (or SYS-BIOS, same thing). So I should be able to port most of that effort to my RTOS, which has much better features (and API) for keeping the apps low-power.
  4. Some information about TI's new IoT radio SoC product line is now trickling-out. CC1310 is a sub-1GHz wireless SoC, and CC26xx units are for 2.4GHz PHYs. Otherwise, these SoCs are basically identical. CC1310 | Sub-1 GHz | Wireless Connectivity | Description & parametrics CC2620 | RF4CE | Wireless Connectivity | Description & parametrics The specs of the CC1310 are absolutely insane. There's no question it is built on a 90nm fab, or maybe even 65nm. It contains 3 MCUs: the main unit (Cortex M3) the radio controller (Cortex M0) and a sensor controller that is some sort of pr
  5. I noticed that the part number in the CCS screenshot is MSP432P401R, so I guess we know that the "4" in "P401R" means Cortex M4. Frankly I wouldn't mind a regular-old M3. M0 and M0+ use a different version of ARM, and there are actually some porting issues between M3/M4 -> M0 ... so I don't mind if M0/M0+ is not in the product family. On the other hand, if I can save some power and cost by choosing M3 instead of M4F, I will usually make that choice. Hardware floating point is not so important for my work.
  6. People in the industry have been dropping me hints for a while that an ARM M0+ with MSP peripherals and clock system is on the way. A few years ago, I lobbied pretty hard for this, so I guess it's nice that things are coming around. Assuming that the resulting device gets Energia support, that would be great. The Atmel ARM CM parts aren't worth using in low power designs (frankly I think they are weak in most respects). The STM32L parts are great, but I would need to port Arduino to them and do all the requisite community marketing: no thanks. I have a pretty nice firmware and IoT pl
  7. Burn em. Friends don't let friends use AVR.
  8. Several years ago I bought a PC logic analyzer from Intronix (http://www.pctestinstruments.com). It is really quite good, but this Analog Discovery product looks much, much better. Seems like a must-buy.
  9. @@smarpl Just out of curiosity, what is the Flash requirement? 16KB? Your blog post seems to indicate that it's advisable to have 1.3KB of SRAM or more. So, perhaps the 5529 Launchpad is the best platform. If there were a 5510 launchpad, I would guess this would also be fine.
  10. The antenna on page 64 (marked as 62) is a quarter wave IFA. This is actually similar to the antenna in the HayTag, except there are some other techniques used to increase the "electrical length" and to improve the size of the ground plane. Too much to explain. The antenna I mean by "omni-dipole" is different. It is just a vertically oriented wire dipole antenna. I usually use a dipole with a big inductive load (i.e. a helical element on each arm) in order to reduce the size. The penalty is bandwidth, but this isn't usually a problem for 433 MHz or 868 MHz usage. For 915 MHz band, it's OK
  11. I want to get a PSoC 5LP kit... the one with the Cortex M CPU. I think I can build an MSK direct-conversion SoC for the LowFER band with it. LowFER is a boutique thing, so the relatively high price of the PSoC is just fine.
  12. LoRa doesn't use DSSS (Direct Sequence Spread Spectrum), it uses CSS (Chirp Spread Spectrum). If you are curious, you can look these up on Wikipedia, the entries there are good. At the end of the day, they have basically the same performance. Spread-Spectrum modulations don't generally improve maximum sensitivity, however they do improve decodability of a message in interference. An optimal spread-spectrum modulation has equivalent SNR to a narrowband modulation. In the real world, it often works better, though. Additionally, for very low data rates, narrowband modulation becomes increasingly
  13. 5km is outdoor line-of-sight at 433 MHz with 11dBm, chip rate 13.24 kHz (actual data rate about 0.4 times that), good antennas (omni dipoles), and using my implementation of the Voyager Code's Reed Solomon error correction in addition to the built-in convolutional coding of the SPIRIT1. I have not actually released the RS code implementation into open source yet. Without the RS, though, 2km outdoor line-of-sight is still quite feasible. In difficult environments, it's more like 300m. This solution will decode packets down to about -118 dBM -- with the SMPS on -- however it doesn't do tremen
  14. Weird. The parametric product table says no AES.
  15. It uses a BSD-style license, so do what you want. It actually uses the "OpenTag License" which gives you some patent rights as well. Yeah, I need to decide what I want to do about my dev kit HW. I don't make money on dev kits, so I'd like to find a clever way to open source it, while still allowing me to collect small royalties for commercial use of the design. CC1200 is better than SPIRIT1 for this. It is a tad more sensitive, but more importantly it has some DSSS features (and a more low-tolerance sync-word setting). To get the advantage of low data rates, you need to do extrem
  16. There is some information leaked on the internet about CC13xx, which appears to be a Cortex M3 + CC1200 SoC. I'm not sure when it is due, but it is an interesting option. If you're going with discrete MCU + RF, I have good support for STM32L1 + SPIRIT1 via OpenTag, and there is some experimental work for the L0 support. In any case, the code is open sourced on my GitHub, so feel free to take a look. If it is between STM32L0 and Zero-Gecko, I would go with the STM32L0 simply because it is more versatile. This way, you can have a single platform for both the endpoint and, presumably, a U
  17. There is no AES on this part. In fact, no Zero-Geckos include AES. AES can actually be a bit of an issue for export restrictions, so don't get it unless you know you need it. Cost matters if you care about production. If you are a hobbyist, frankly, I think you should care more about how quickly/easily you can realize the goal far more than you should care about cost, but nonetheless I have encountered a lot of folks stressing-out over a dollar here or there. Anyway, the price on these parts is outrageous. SiLabs cannot be making money on these. But, a race to the bottom for the m
  18. The mouser pricing seems like it's promotional. In any case, it is good to see that the price has come down. One caveat about Zero-Gecko, though, is that it is only 32KB Flash + 4KB RAM, and there is no AES HW. In September, I bought a tray of 50 STM32L062K8 parts from Future for under $2/unit. This is obviously $0.70 greater than the price of the Zero-Gecko, but the device has 64KB Flash, 8KB RAM, 2KB EEPROM, crystal-less USB, and HW AES. For doing IoT stuff, the AES and EEPROM are good to have. The extra RAM doesn't hurt. Many of the MSP430F5 devices have USB and AES, and the FR ones
  19. I feel bad about saying this on an MSP430 site, but really, really, really... the MSP430 is not getting chosen for new designs in IoT stuff. If you are a TI dedicate, this might be OK, since there is a little bit of leaked information about CC13xx on the internet... you can probably guess what it is (good night CC430). And no, I do not have an active NDA with TI. I've said for a long time that TI should upgrade MSP to CM0+ and just keep the same clocking and peripherals. A good Cortex M0+ like the STM32L0, EFM32-Zero, or the equivalent Freescale part (I am not familiar with their naming
  20. This is wrong. I won't get started about HAM and ARRL, and how they destroy innovation in the modern era. But at least you can figure out my opinion. Lower wavelengths represent smaller particles via the wave-particle duality, more smaller particles can be produced with a given energy level, and therefore lower wavelengths propagate better through any medium. What I assume this question and answer refer-to is practice rather than theory. In a concrete bunker, VHF will propagate through the bunker much better than UHF. In a building with windows and doorways, there are situations wh
  21. Outdoor line-of-sight, yes. Indoor, or non-line-of-sight, no. Even a system with a lousy 433 MHz antenna will grossly outperform a system with an ideal 2.4 GHz antenna, non-line-of-sight. 900MHz is somewhere in the middle. The other thing is that you can usually cut a slot in the ground plane, use a small magnetic loop, or do other things to trade bandwidth for efficiency in a compact antenna. For the 900 MHz band, you need quite a lot of bandwidth to comply with both EU and US regulations, so this is actually the largest antenna. 433 is global and has a narrow band, so you can use a s
  22. One common mistake is to assume that such a thing as a 1/4 wave resonant antenna exists. The truth is, there must be a 1/2 wave dipole, or you must have a ground plane acting as a counterpoise to your 1/4 monopole, and this needs to be effectively 1/4 wave itself. Alternatively, there is a loop antenna structure. Small chip antennas are generally a capacitive load combined with an inductive load. This can reduce the size of the antenna, but nothing comes for free. bandwidth is usually less, and efficiency is usually less. There is all kinds of science, engineering, and clever tricks f
  23. My advice is actually to buy a module with an integrated antenna. For 2.45 GHz, it's ridiculous to use an SMA connector which is, in all likelihood, damn near as big as the antenna itself. Just scrape-off the antenna trace with a razor blade, and solder your antenna assembly to the lead. This way, you also have a reference that you can compare your antenna design against. Building a patch antenna for 2.45GHz shouldn't be too hard. However, you must be very precise with the dielectric layer. If the width of the dielectric layer not engineered to a tight tolerance, it will affect the resonan
  24. Flexible PV is hard to buy in low quantity. Panasonic/Sanyo is a major supplier, but you need to be a quantity buyer. Their product line is called "Amorton." ST is supposed to be ready soon with its own flexible PV line, but I expect it will also have quantity restrictions.
  25. "Lithium Thin Film" is a technology, not a description (this is confusing). It uses semiconductor manufacturing techniques to build the lithium ion battery onto a silicon substrate, so it is not flexible. Lithium polymer technology builds the battery on a polymer substrate. The distributor Powerstream (powerstream.com) is the best place to look for LiPoly, and I believe they distribute some thin, flexible models of LiPoly.
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