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Forum Index : Microcontroller and PC projects : pin soldering problem
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| Andrew_G Guru  Joined: 18/10/2016 Location: AustraliaPosts: 842 |
Thanks WW, a great response. Yes I was referring to an equivalent pinout for a PIC32MX170 28 pin chip but on the 5V tolerant list I (mistakenly) referred to the QFN pin numbers which are beside them on the schematic I was looking at. Hence I listed 18-19 instead of 21,22. (No idea where I got that pin 1 was 5V tolerant - its not in the manual!) Once again on the schematic, I described the extra two pins as "after pin 14" and "before pin 15" (ie at the bottom of the chip). In the "blurb" on the Rictech website they talk about feeding in between 4 and 16V to power the unit (with the USB disconnected). You are warning that this might be too much?? Thanks again, Andrew (By the way my 1.8" 128x160 non-touch LCD is working nicely - it shows GPS speed on my dashboard with the text colour changing if I go over a "speed limit". We have several sites where the system records you average speed over say 5km and issues a fine if it thinks fit - the next version will average my speed between two button presses) - A |
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Grogster Admin Group  Joined: 31/12/2012 Location: New ZealandPosts: 9066 |
Hello.  I need to update the 'Blurb'. I will be doing this soon-ish, to reflect the new SOIC design and the 1C version of the PCB. The 1703A regulator used on the board to supply 3v3 to the PIC32 and 1455 USB interface chip, can accept up to 16v input, but as WW has already pointed out, things might get a little hot with a higher input voltage. I also recommend sticking to a 5v input voltage - either via the USB cable, or via the 5v input pin on the edge of the module. The module would be happy enough at up to 9v input, so long as you don't source or sink too much current via the 170 I/O pins, and/or suck too much current from the 3v3 output pin. Assuming 5v input, the regulator only gets warm - even with a bit of action on the I/O pins. The design uses the USB shell itself as a form of heatsinking. At 9v, the regulator will get hot with the same I/O pin load, and at 12v or more, it may well shut down due to overheating. The official line at this stage is: Recommended supply 5v, Maximum supply 9v, Absolute Maximum 12v(not recommended). Smoke makes things work. When the smoke gets out, it stops! |
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| robert.rozee Guru Joined: 31/12/2012 Location: New ZealandPosts: 2291 |
addendum: oops, i was writing my post while grogster was posting his! here is the schematic for version 1C of the E-28 module: 2017-05-06_130726_E-28_1C_diagram.pdf we will be creating an updated blurb for the 1C over the next few weeks. the main design goals for the E-28 were: 1. to fit into the same 30-pin 0.6" DIP footprint as an Arduino NANO, 2. to have an onboard USB interface, just like the NANO, 3. for 27/28 of the pins to have, as much as possible, the same functions as the corresponding pin on a 28-pin SDIP MX170 (the other 2 pins function as +5v out or 5-16v in). externally, the E-28 behaves exactly like 28-pin SDIP MX170 except: - all Vcc pins are already connected together and fed by a 3v3 regulator, - all ground pins are already connected together, - the console (pins 11 and 12) is serviced by the USB bridge, - pin 20 is omitted as there is an onboard 10uF capacitor. the MCP1703A regulator used on the E-28 is capable of handling up to 16v input, however you would be advised to limit current drive from output pins if feeding in the full 16v so as to avoid excessive heat dissipation by the regulator. 4xAA cells giving 6v is just fine, a 9v battery is moderately ok but a rather expensive power source, 12v (typically 13.8v) from a car electrical system is probably a bad idea as there likely will be transients that exceed the rating of the MCP1703A. cheers, rob :-) |
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| isochronic Guru Joined: 21/01/2012 Location: AustraliaPosts: 689 |
Is it 4 layer still? Microblock's SSOP design looked pretty good |
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| Andrew_G Guru Joined: 18/10/2016 Location: AustraliaPosts: 842 |
Grogster, Rob and WW, Thanks for clarifying that. My eyes lit up when I saw the 16V but there is no point pushing it too hard. Some of my projects will be in a car or yacht and as Rob says 13.8 or more is likely (mostly driving an LCD display). I'll just have to use some form of pre-regulator to get it to 5V. I (and many others) am still keen to get my hands on some when I can. Thanks again, Andrew |
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| Andrew_G Guru Joined: 18/10/2016 Location: AustraliaPosts: 842 |
Rob, Thanks for the updated schematic. It really clarifies the 1:1 with the mm170. Cheers, Andrew |
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