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Today we have finalized the required changes for the HW of the device, defining the Revisions. The main changes are:

  1. Change of the enclosure to a bigger one, introducing the pumps
  2. Moving the LED dimming electronic components as far from the analogue sensors electronics as possible
  3. Changing the battery type to 2032
  4. Adding a 12V output for future use
  5. Adding a HW watchdog – adding a small ATMEGA chip with improved ADC
  6. Adding possibility to measure current passing through the device
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When we have almost everything ready, I have decided to make a significant change to the device. The reason is, that I believe it will dramatically improve the added value of the device for user, while being a relatively simple change in terms of technology. We will include in the device also 2 pumps for automated liquid fertilized dosing. From the SW point of view, we will reuse a lot of what we already have implemented, just modifying it a bit. From HW point of view, this will introduce the pumps, which we need to operate from the chip. Luckily enough, we still have enough free pins to introduce this feature. We will also introduce a couple of improvements for the device, which I am going to go into detail a bit later.

I have ordered samples of the pumps and also a bigger box to house the improved PCB. This first sample is a bit small, unfortunately.

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Apart of other tasks, we are also solving the issue of the time of the device. The thing is that we expect to have devices in several countries and possibly in several time zones. For this reason, we settled for using the UTC in all devices and the application has to translate this into the local time zone of the user. We have waited with the implementation, because it was not a primary goal. But now we have done also this change.

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I have been spending quite a lot of time with improving the pH calibration function. We need to find the right balance between the speed of the pH change and the moment when the only deviation from the measurement is the analogue & digital noise created by the components. We are able to measure pH with 0.01 precision, which is absurd for use in an aquarium, yet we struggle how to exchange portion of this precision for the calibration function simplification. This is how my desk looks these days.

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We continue to test the PAR sensor with various LED lights. It turns out, that the sensor is very precise and calibrated, but we will need to introduce the calibration of this sensor as well, in order to solve the small differences on the ADC used to read the measuring.

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It seems we might be more lucky this time with the mobile developer. We have received around 90 proposals from people willing to do the job. Out of these, there were 58 who were willing to continue even as we said the first part of the job is unpaid – for us to see the quality of the work.

In the end 10 people actually delivered a result, 2 of them a good one.

We chose to work with Mati, who delivered exceptionally. In 2 hours, he has pushed the correct code to the repository. I will just say, that there were developers, who estimated the work for 2 weeks full time.

So we are very glad to have Mati in our team.

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It turned out, that Methos really does not have as much free time to spend on the project as we would need. We decided we would give the freelancing server another try, but this time, we will be much more picky. We have created 3 simple tasks, which will show us how the developer understands the requirements and how is she/he able to incorporate required changes.

For each contestant we will create a separate repository into which we expect the results delivered.