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Lake Malawi

April 12 2014
Plan is to look for new Places to collect ornamental fishes. These can be collected from 0 to arround 40 meters by hooka-system. Additional info: Lake Malawi is the most southern of the African Great Rift Lakes. It is shared by the countries of Malawi on the western and southeastern shores, Mozambique on the central eastern shore, and Tanzania along the northeastern shore and at the extreme northwest. It is the third-largest lake in Africa (31,000 km²; 603 km long × 87 km wide), and the tenth-largest in the world. Its surface is around 474 meters (1555 feet) above mean sea level; its maximum depth is some 704 meters (2310 feet), making it the world's fourth-deepest lake.

April 12 2014


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Preparation Stage

It's been a while on my updates, as time haven't been on my side for this project.

I have build a mapping drone that will be used together with rest of equipment. Picture is from testfitting before installing Electronics in it. Controller will be Pixhawk



Sorry for not updating for long time, but too much work and not enough hours...

Here's a more complete picture of setup with the 320x240 touch display planned for the logger

There's still room for much improvement on the amount of space not used.

so plan in schrinking it as much as possible.


Sensor board allmost ready for first test


Finally quad band gsm and GPS module arrived


Discovered that I was programming Arduino in 0022 and they moved to 1.0.6 now with a few changes esp. on Serial.print

Suddently my code doesn't work after migrating to the 1.0.6 as it keeps writing to SD card without closing file so back to work on my software again


Alternative storage if uDrive system crashes


And some more work on a op-amp circuitry so I can control gain tru sw.

Maxim DG202AK for the interrested people


As sw now running "perfectly" I just had another (bright?) idea...

Datalogger could send live measurements to my website via GSM or GPRS.

So found this module that includes a GPS as well.

Rather cheap compared to other types of GSM/GPRS stuff and you get GPS.

So problem is now some way to store data on my ASP website and if possible also show it as graphs/bars..

Sorry for long delay in updates from me.
Well started new job as technitian at so not a lot progress made with this project as didn't have much time.

First off struggeling with some strange SW problem averaging on a different sensor than on my last post's

This sensor

My Arduino code is as follows:
Trying to find the fault in String Temp_water() I have added 3 Serial.print

First one gives correct value out - This one:

Serial.println (readings[index]);

Next 2 are off in values, but I can't see why...

Serial.println (total); and

Serial.println (average);

Data on serial port:
Serial.println (readings[index]);24.18
Serial.println (total);145.07
Serial.println (average);29.01

Bit heat from my hand on sensor and temp goes up:
Serial.println (readings[index]);27.31
Serial.println (total);152.85
Serial.println (average);30.57

Value of average matches ok with total as that is 1/5 value

float water_temp; //

float Thermistor(int RawADC)

long Resistance;
float Temp; // Dual-Purpose variable to save space.
float pad = 10010; // balance/pad resistor , set this to
// the measured resistance of your pad resistor

Resistance=((1024 * pad / RawADC) - pad);
Temp = log(Resistance); // Saving the Log(resistance) so not to calculate it 4 times later
Temp = 1 / (0.001129148 + (0.000234125 * Temp) + (0.0000000876741 * Temp * Temp * Temp));
Temp = Temp - 273.15; // Convert Kelvin to Celsius

water_temp = Temp;

return Temp;


String Tempwater()
digitalWrite (Vcc
temp_water ,HIGH); // Enable VCC

delay(50); // Delay a bit... to stabilize VCC

// Define the number of samples to keep track of. The higher the number,
// the more the readings will be smoothed, but the slower the output will
// respond to the input. Using a constant rather than a normal variable lets
// use this value to determine the size of the readings array.
const int numReadings = 5;

static float readings[numReadings] = { 0.0 }; // the readings from the analog input

static int index = 0; // the index of the current reading

static float total = 0; // the running total

static float average = 0; // the average

static bool initialized = false;

if (!initialized) {
average = Thermistor(analogRead(ThermistorPIN)); // read ADC and convert it to Celsius
for (int no = 0; no <= numReadings; no++)
readings[no] = average;
total = total + average;
initialized = true;

// subtract the last reading:

total= total - readings[index];
// read from the sensor:
readings[index] = Thermistor(analogRead(ThermistorPIN)); // read ADC and convert it to Celsius
Serial.println (readings[index]);
// add the reading to the total:
total= total + readings[index];
// advance to the next position in the array:
index = index + 1;

// if we're at the end of the array...
if (index >= numReadings)
// ...wrap around to the beginning:
index = 0;
// calculate the average:
Serial.println (total);
average = total / numReadings;

Serial.println (average);

String stringResult = "";
int tempheltal = (int)average;
int temp
decimal = (int)((average - (float)tempheltal)*100);
stringResult = stringResult + temp
heltal + "," + temp_decimal;

digitalWrite(Vcctempwater ,LOW); // disable VCC

return stringResult;


I love that you are making progress in the sensor direction, coding an arduino is beyond my skill set at this point, but I bet some hackers on the forums at would be an amazing help. There is a whole heap of software engineers who can help point you in the right direction. Are you chatting with anyone over there?

Did make a post there but at moment 0 replies. Looks like I found the fault as when you start out with const int numReadings = 5; It's actually 6 times as it begins from 0 to 5 = 6.
Fix is : for (int no = 0; no < numReadings; no++)

Nice to order parts to find out there's 6-8 weeks delivery time due to spec. ADC that no one in Europe stock...

Oh no! Which parts?

It's a Analog Devices spec. video AD converter.

Even worse news, they have now sent me 2 WRONG ADC's and by the look of it middle or end May before I have the right ones... But had to change supplier for that to happen...

David, here's a Picture for You!



Handsoldered and with 4 mistakes if you look closely at the far side of it...

Some parts soldered, just need to order the rest...


Fits like a glove :D

Just need to find time to start hand solder it...


Oh boy! That's going to be a tough one. good luck!

U2 is not difficult, look at the Picture below in upper right corner...
R4 will be difficult its small size 0201. Compare with C11 that is a 0402, L1 0603...

Text size of 30 is not good , maybe 32 is smallest they can handle...


Quality looks ok, thinnest lanes are 6mill in width


Today pcb and stuff arrived without customs problems.

Shipping time from Elecrow is ok fast to Denmark.

Here's Pictures of the PCB's


This Fellow arrived today. Looks good with soldering and so on.

So it's time to struggle with sw....


Excited to see how this works underwater!!

I have an plan to find a crylic tube and try to test it in my aquarium. Just a thought on the ROV's tube, as sensor is inside and light shines on the tube wouldn't it attract more light to the sensor due to the tube shape as it would act as a lightguide... Don't know if it makes any sense...

This was a nice mail to get a Picture with items ordered ready to ship!

Seems they are working rather fast to make the PCB's - Next thing is how the quality is...


I'm eager to see how the color sensor works!

I'm also , sadly it's too big to fit inside the ROV.
But I have ordered this one as well to go inside ROV as it doesn't take up much space.

A video from the lake so you have an idea on how it looks.

All of these fish are aquarium fishes and some rather rare

No hippos? :)

Oh no! But think I have video of hippoes taken at a safe distance. Don't want to end my life as a hippo's toothpick...

Short update on colorsensor(s)...

Just bought this on ebay, much cheaper than a diy for test if it can be used insode the ROV..

Also finally ordered pcb after latest changes for my 8color sensor, hope all mistakes have been removed.


What was the lead time? In stock?

Ebay sensor in the link is in stock, at moment they have 6 pcs..

PCB I ordered from Elecrow as they are cheapest I have found for this small quantity that I need. I save allmost 40 USD by ordering 10pcs from them compared to other companies that only will make 1 pcs.

After some thoughts about bringing loads of equipment I deciced to try and make a small portable charger.

I did some research on different charging IC's and at first Texas BQ2054 looked good untill Guys at OpenROV HQ decided they want to change batteries from LIPO to LiFePo4..

I ended up with the Linear LT3562HVEMSE that is a multi-charger IC.

Datasheet can be found here:

This Circuit isn't final-tested yet, only made in Eagle so it's "as is"


Lane width is calculated using

Don't know if it's worth redesigning pcb's for:
1) Able to use laptop charger - saves Space on equipment to bring with
2) Fan control to limit temperatures of the two charger ic's to avoid burning them out.

Finally some official info on the new batteries planned for the OpenROV:

Loads of testing with solar panels and I have ended up with 12 small panels that can at best produce 5V and 1,2A

Still working on the color sensor after finding few faults in my layout...


What brand or model are you using? Did you test different kinds?

I did a lot of google'ing seaching for the cheaper panels and found these at I use the 0,5W panels as they are small and easier to fit inside a bag or the box when travelling. My tests was how many I need here in northern Denmark as we don't have much sun compared to many other places. With this amount it charges when there's not lot of sun. Of cause I could redo the charger as it's this but will be using it for for now.

Yes and commented as well :)

First try on the color sensor pcb, still needs few changes.

Not sure if it should be stackable or "just" with wires.


This looks awesome. What are the 8 colors you are setting it up to recognize? Do you program it to a range of nm or a set value for each color?

I plan for these colors, measured individually on seperate channels:
695nm 10 bandwith
670nm 20
615nm 15
557nm 15
515nm 15
490nm 10
460nm 10
428nm 10

With range, offset and PGC adjustments controlled by sw before saving data.
Also an extra Lux Measurement if these will overload as it will be close to equator and not sure if I here in Denmark will be able to test with our amount of daylight.

Logger coming a lot further now..

Need to get a pcb made to get last 8-color sensor in place.

After last post with the logger it came to my mind that in Africa you have lot of heat that most Electronics don't like.

The extra sensor pcb will also have automated fan control starting at 45 degrees C and shutting off arround 30 degrees C.

As you can see with the box size I plan to use a small 5V fan to try and keep the heat Down.

Biggest problem is still the sw..


Please note Malawi still have lot of wildlife and now also the first 3 lions since 1980'ies.

Do be carefull when moving arround as You may run into different not so nice animals.

Notice distance from Beach to hippo in front , that is right in front of house where base is.


Wow! You really go diving with hippos around??

An definitely not! That will get you killed fast...
We where swimming there 5mins before that head popped out of the Water.. Was sitting at the porch relaxing after a dip in the lake... So after that we allways ask local people if there's hippo or croc arround :D

What I allways bring and have sorted out before I travel as weight is a problem:

Places to visit for diving and exploring
Own dictionary with local names.
Books - esp. Lonely Planet.

Air ticket - remember extra bag for gear may be necessary due to weight!

Visa - if needed
Insurance - also for equipment
Money - USD

Vaccinations - yellow fever, hepatitis, diphtheria, tetanus BUT ALLWAYS CONSULT A DOCTOR BEFORE TRAVELLING

Medication - diarrea, seasickness, eardrops against Inflammation of the middle ear due to lots of diving.
Sunblock - the higher number the better as You are straight beneath the sun and out on a lake.
Mosquito repellant
Soap, deoderant, shavingtools, towel,
Hypodermic needles, patches and similar.

Travel adapter as Malawi use UK plugs.
Extra batteries for camera, videocamera, cameraflash, flashlight, GPS.
Cardreader to empty cameracards
Bag for camera's

sleeping pad
Zipp-off pants - good for traveling as you come from colder weather to warm
cap foreign legion style as it gives shade to neck to avoid sunburn
Running Shoes - most comfordable as sandals aren't nice with sand in

Zip-it bags, stickers, ball-pen for notes
Padlocks - for cases, sadly if they can steal it they will!
duct tape - of cause!
Additional lenses
Underwater housings
fine-meshed nets

ABC scubagear - mask, fins, snorkel
Spareparts for scubagear: mouthpieces, mask strap, O-rings and grease
Tools for fixing scuba
Shorty divesuit, kneepads as you move arround on rocks to catch fish,
Divelight, speargun, ponybottle

Adresses for postcards, phonenumbers to relatives if any problems occur.

Here's also a good packinglist if you plan to drive arround:

Expedition Background

All my trips are based at a collectingstation in Chipoka where we sail out from to the different Places.

Plan is to use Fisfinder/Plotter to find reefs and then deploy OpenROV to explore , this saves a lot of time compared to going in with scuba.

Following equipment must be small, handy and have low power consumption:
Fishfinder/plotter combo
OpenROV (Of cause!)

My own stand-alone DIY logger (In development):
Water values: Ph, ORP,Conductivity, temperature.
Above water: wind speed and direction, Rain, Light in Lux and RGB colours, Pressure (mbar), temperature and humidity.
A camera is taking pictures of the lake for comparison to data on it's own SD.
All measurements are marked by time taken from a RTC
Solar-charger as backup for uC (6A LiPO)
Data stored on uSD

Some kind of solar charger as most collecting trips easily are 5 days at remote Places without electricity and just sleeping in a tent on the Beach.

Logger is now in Our livingroom window to see if solar panels can generate eanough power to drive and charge the battery with the amount of sun here in Denmark.

One solar panel can generate 100mA and system have 7. for Denmark that is not good eanough.

Need to sort out way to switch off power supply to different circuitry to save power when they aren't in use.

Video on how they catch fish in Malawi, underwater from arround 10:10


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