Safe and Sound: Winter Survival Suit Post #8

This week’s update is about the temperature sensors and dealing with the possibility of moisture issues.

First is the temperature sensors:

I finally received the temperature sensors yesterday!! I have been working most of today with Energia to get them working. At the time of writing this blog I am still working on the script. I will post an update blog when it’s up and running. The sensors are the DS18B20 Temperature Sensors. OneWire requires a single 4.7K pullup resistor, connected between the pin and +5 volts. Then just connect each 1-wire device to the pin and ground. Some 1-wire devices can also connect to power, or get their power from the signal wire. It looks like I made a bit more work for myself ordering this type of sensor. This Maxim series temperature sensor works on the Maxim OneWire protocol which needs a single contact serial interface. I downloaded the libraries “OneWire-master” and “Dallas Temperature” then transferred them into the libraries folder in Energia. It looks like I will be doing some re-programming of my script to get the MSP432 to read the sensors. At least I can move forward on my project!!

This information was copied from https://www.pjrc.com/teensy/td_libs_OneWire.html

Basic Usage

OneWire myWire(pin)

Create the OneWire object, using a specific pin. Even though you
can connect many 1 wire devices to the same pin, if you have a large number,
smaller groups each on their own pin can help isolate wiring problems. You can
create multiple OneWire objects, one for each pin.

myWire.search(addrArray)

Search for the next device. The addrArray is an 8 byte array. If
a device is found, addrArray is filled with the device's address and true is
returned. If no more devices are found, false is returned.

myWire.reset_search()

Begin a new search. The next use of search will begin at the
first device.

myWire.reset()

Reset the 1-wire bus. Usually this is needed before communicating
with any device.

myWire.select(addrArray)

Select a device based on its address. After a reset, this is
needed to choose which device you will use, and then all communication will be
with that device, until another reset.

myWire.skip()

Skip the device selection. This only works if you have a single
device, but you can avoid searching and use this to immediatly access your
device.

myWire.write(num);

Write a byte.

myWire.write(num, 1);

Write a byte, and leave power applied to the 1 wire bus.

myWire.read()

Read a byte.

myWire.crc8(dataArray, length)

Compute a CRC check on an array of data.

Second is the moisture issue:

I have purchased a liquid that can be applied to the electronic circuits that protects them against moisture and other environmental concerns. I added the product description below. The cost was $23 cdn through Amazon.

MG Chemicals Acrylic Lacquer Conformal Coating

• 419C Acrylic Conformal Coating is an IPC 830 certified, fast drying, xylene and toluene free product that provides an excellent finish. It is easy to use and does not require special or costly equipment to apply
• It is ideal for high moisture environments and applications requiring easy repair and rework
• The 419C coating protects electric circuit against moisture, dirt, dust, thermal shocks, and scratches that could corrode, short circuit, or otherwise damage the electric component
• It insulate against high-voltage arcing, shorts and static discharges; this coating provides high dielectric withstand voltage allows traces to be put closer together helping with miniaturization

Product description

419C Acrylic Conformal Coating is an IPC 830 certified, fast drying, xylene and toluene free product that provides an excellent finish. It is easy to use and does not require special or costly equipment to apply. It is ideal for high moisture environments and applications requiring easy repair and rework. The 419C coating protects electric circuit against moisture, dirt, dust, thermal shocks, and scratches that could corrode, short circuit, or otherwise damage the electric component. It insulates against high-voltage arcing, shorts, and static discharges. As well as, this coating provides a high dielectric withstand voltage that allows traces to be put closer together helping with miniaturization. Super fast cure - reduces production and maintenance bottlenecks. No hazardous air pollutants - free of toluene and xylene. Externally qualified to IPC-CC-830B by Pacific Testing Laboratories, Inc. Meets UL 94V-0. UL Recognized. Excellent finish - smooth, homogeneous, and durable crystal clear coat. Protects electronics from moisture, corrosion, fungus, and static discharges. Easy to inspect - fluoresces under UV. Easy rework and repairs - can solder through coat; remove with MG Chemicals Thinner/Cleaner or Conformal Coating Stripper. Visual crystal clear color. Excellent solderability, weather resistance, fungus resistance, flexibility, moisture and insulation resistance and thermal shock. 94V-0 Flammability. Ether-like, gasoline and minty odor. 3-5 minutes tack free. 2 minutes recoat time. 24 hours full cure (at room temperature). 30 minutes full cure (at 65 degree C /149 degreee F). -65 to 125 degree C service temperature. Less than 12 800 sq cm (less than 13.7 sq ft) maximum coverage for 25 micrometer (1 mil). ROHS Compliant.

Thank you

Dale Winhold