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ESI Project: Laser coolant monitor


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My ESI project entry should be a fairly simple one. The first sentence describing the ESI is as follows: "The Extended Scan Interface (ESI) peripheral automatically scans sensors and measures linear or

rotational motion." Luckily that's exactly what I'll be doing. I won't be pushing the ESI to its limits or bending it to some cool new purpose. However that should mean that I'll be able to get a clear idea of what the ESI does and how to use it properly.
 
My project is to measure the flow and temperature of the coolant in my laser cutter. It's one of the cheap DC-K40 ones that you see all over eBay and as such it's very basic. It has an aquarium pump to push some coolant through the glass laser tube. This is entirely separate from the rest of the laser and seems almost like an afterthought. If you forget to switch it on before cutting - you'll quickly destroy the tube. If you let it get too hot - you'll quickly destroy the tube. If the pump fails or a tube falls off - you get the idea.
 
As this seemed like something I was bound to do sooner or later, I've actually already made version 1.0 of my coolant monitor. It uses a MSP430G2533 and Timer_A to count the pulses from a hall effect sensor. If there are less than a certain threshold over a fix period then the laser is disabled. There's also an LM35DZ temperature sensor. Exceeding a temperature threshold will also disable the laser. These are mounted where the water exits the laser tube. It's happily protecting me from my own stupidity. It's nothing particularly special but I did a quick write-up here: http://0xfred.wordpress.com/2014/06/03/laser-improvements-coolant-monitoring/
 
So why move over to using the ESI? To be honest - just to find out about something new. My G2533 based circuit does the job. If the manufacturer had bother to implement anything and was doing it as cheaply as possible it could probably be done with a comparator, some resistors and capacitors. One benefit of the ESI approach would be lower power - but I've got a 40W laser running anyway. Another would be offloading this task so the MSP430 can get on with something more interesting - that I might be able to use later.
 
For now though - I just want to find out about the ESI. Maybe I'll get some inspiration once I find out what it can do. The other burning question though... can I home etch and solder TQFP?
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My TS430PZ100D target board arrived today. All seems to work OK with the older FET430-UIF. I used to wonder with those ZIF sockets were so expensive but having seen one up close it seems a little more

Another thing I noticed is that when using the MSP-FET instead of my MSP-FET430UIF I immediately got an EnergyTrace window showing up. Without even digging into the detail it already looks really usef

The first part of the ESI I've looked at is the Processing State Machine. The best explanation seems to be in section 4.7 of slaa639 which explains the LC base quadrature encoder example. It's particu

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One thing lasers aren't great for is making PCBs. It's possible to use black spray paint on copper class board and laser it off before etching, but to be honest there are easier ways to do it. Laser cutting or drilling FR4 doesn't work that well either. You can use it to make Mylar solder stencils though.

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Wlist waiting for my kit (Thanks, TI!) I've been doing some reading up on the ESI. It's quite a daunting peripheral to start with. I was starting to wonder if the ESI alone was more complicated than some of the simpler MSP430s.
 
However, reading the datasheet along with the very helpful reference designs makes things much easier. Simplifying things greatly the ESI is designed to keep both your sensors and MCU powered down most of the time. It powers the sensors up periodically, takes readings and processes these without having to bother your processor. The reference designs are based round optical, LC or GMR sensors, but the datasheet states that the ESI can also work with simpler digital or analogue sensors. My eBay flow meter is I believe a hall effect switch so that should be fine. It might also work with my LM35 temperature sensor too as that gives an output voltage of 10mV per celcius.

 

Well, that's enough for now. It should be easier when I have something to work with in front of me.

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My TS430PZ100D target board arrived today. All seems to work OK with the older FET430-UIF. I used to wonder with those ZIF sockets were so expensive but having seen one up close it seems a little more reasonable. Some tips if you're also using one:

  •  You press down to open the ZIF socket, drop the IC in and the let it spring up to grip.
  •  If you've not worked up close with LQFP before, the pin 1 marker is the smaller one in the bottom left, so this lines up with the arrow on the ZIF socket. Text is printed in different orientations on everything so ignore that completely. Also ignore the two larger circles on the IC.

 

I'm still waiting on the other components I need, so I just fired up blinky to test everything was working. If you look at the CCS generated blinky code it includes a line to disable the default GPIO high impedence mode. I would probably have been caught out by this if I hadn't been so lazy I couldn't write my own blinky code!

 

I would play a little more but I'm just off to finish laser cutting some stuff for @@PTB from that PoTM contest way back in March.

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It's maybe worth noting, as you have, the PZ100D has an indicator in the silkscreen on the board showing where pin 1 should be. The chip should be placed in the socket, labels facing up, and provided you have the kit with the JTAG header to your right, pin 1 would be located bottom left. Worth noting is the socket also has an arrow indicating where pin 1 should be.

 

The Rev C chips have two large dots at opposing corners, and a smaller dot at a different corner: THAT SMALLER DOT is the pin 1 indicator.

 

So now you know how to get the chip in... do you know how to get it out? Simply turn the board upside-down and press on the socket, and the chip should drop out.

 

 

And my apologies if what I wrote seems condescending. Some of us have never dealt with sockets such as these, so I'm only writing up what I observe.

 

Now, if Energia supported MSP-FET and the FR6989 chips, I'd be ... well never mind. That's my fantasy. :D

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No problem. That didn't sound condescending, but did sort of just repeat what I'd said. I know how to get the chip out because... well guess how I found out that those two large dots aren't for pin 1! I can also confirm that putting it in the wrong way round doesn't damage it. :) Not tried upside down.

 

I must admit I don't get the whole Energia thing. I feel you lose (breakpoints and debugging) far more than you gain. Grace can be a bit of a timesaver though. That definitely doesn't support bigger stuff or the ESI either. However if you depend on either of these then the FR6989 might be a bit too much to handle.

 

Anyway, back on topic...

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