USB first appeared in the 1990s, aimed to simplify the connection of peripherals and PCs and eliminate the extension of various traditional interfaces. More than 20 years later, it not only achieves the original goal, but also becomes a standard of charging and powering a variety of personal electronic products. If you have asked someone in 1995, if you can make USB-powered soldering iron, they will definitely laugh at you, or politely asking you to leave USB technology forum, this is not funny.
but! ! ! The times changed, Solder Ninja is like this!
Solder Ninja maximum power consumption is 40 W, which needs to be carefully designed to ensure practicality. It supports various USB power standards, including USB-BC 1.2, USB fast charging, and USB power supply. This allows it to absorb a large amount of current required for the heating element. In order to facilitate the use of various chargers in the wild, it displays the voltage and maximum current consumption under current operating conditions. This allows the user to understand the different properties of the device, depending on the inserted charger.
Solder Ninja is a two-year venture trial project designed to make electronic devices easier to use by creating a durable and reasonable tool, thereby making up the gap between cheaper large soldering iron and professional soldering stations.
It has a USB TYPE-C connector that powers with any USB charger, a portable battery or compatible computer. Acceptable voltage ranges from 5V to 20V DC. Current firmware supports a variety of power protocol strategies:
USB BC 1.2,
USB fast charging,
- USB power transmission.
When submitting this project, the prototype phase is over. However, I intend to share two parts:
- Review the various challenges and decisions faced by the discussions,
- And updates to the upcoming challenges of the manufacturing phase.
I know that the following statements may make some people feel uneasy. However, open source is something I truly believe. On this project, I began to realize that there is a difference between manufacturing design and open source design, which makes not every project's resources are ideal.
In the early stage, when I asked myself how to open the project, I found myself to face a contradiction: I am doing the same technical choice, one is to make it an attractive product, but to prevent people from using me immediately Will share the content.
We specially consider the following three examples:
CNC machining aluminum body makes a compact and robust device, and allows for components that do not need to screw through small and crowded PCBs, it may be a quantity of 3D printing part of a price of ten times, the number is one.
The depth milling of the board allows the thermocouple to be placed to the digital converter as close as possible to the tip connector to increase the accuracy, which is a very small circuit board manufacturer to provide the original and / or reasonable cost option.
STM32 is used on the Atmega microcontroller because the smaller placeholder area can be increased, and the circuit board can be maintained to maintain the miniaturization of the device. But for developers from the Arduino environment, this also means a higher learning curve.
Therefore, I decided to expand the scope of this project to two aspects:
Create, manufacturing, and commercialization, compact finished products.
Release a slightly modified version, all files open source so that anyone can be cloned, adapt to their needs, production and improvement.
I totally intend to record these two aspects. I realized that this means more jobs for me compared to only one device. But I believe this is the best way.
Review: Temperature measurement, calibration and accuracy
Weller RT skill is a great engineering project. Some people have disassemble them. They embed a small heating element and thermocouple, which is only exposed to 3 contacts of the 3.5mm jack connector.
The thermocouple utilizes the SEEBEK effect through which the conductor of the two different materials connected at one end generates a voltage difference only at the other end, and the voltage difference is proportional to the temperature difference of its length. The thermocouple is arranged according to the material used.
Although I said, I want to talk about temperature accuracy. Honestly, this may be what I think I will spend more time. The reason is very simple: there is not much information about the type of thermocouple inside the Weller RT tip.
I found that internal thermocouples may be D-type or more common K-type, which is a contradictory recommendation. But even if I know the type of thermocouple, I still have to find a way to ensure that the measurement is correct. So I thought for a while, how can I calibrate what will be used above 300 ° C?
My initial idea is to use the melting point and boiling point of water, and the changes in the atmospheric pressure are used aside, and it is desirable to respond to sufficient linearity in response to a two-point calibration at 0 ° C and 100 ° C. Still up until 400 ° C. .
Then I accidentally discovered HAKKO FG-100, which is a calibration device designed for the soldering iron, promotes the tolerance of +/- 3 ° C. I have made some measurements and identified a linear law to adjust the current Maxim MAX31855 K-type thermocouple to digital converter reading.
Review: Charger compatibility, variable input power and user experience
About two years ago, when I first started the work of this project, USB TYPE-C was slowlycoming a thing, and the Power Delivery, which is expected to provide up to 100W power.
However, the USB charger is now everywhere, I think this point is meaningless from the perspective of the environment, and for those in stock through the device and sell USB charger. Instead, people will use themselves.
This means adding support for current non-USB TYPE-C chargers. Mobile phone manufacturers have long realized that the traditional 5V / 0.5a is not enough, and proposes various solutions, including the use of resistors on the data cable, allowing up to 5V 2.4A, or high-pass fast charging mode in data Online uses different voltage levels, allowing up to 12V / 1.5A.
I hope that regardless of the power type of the user inserting the device, you should try the maximum power of the protocol. But follow, there is a problem. This means that the same device can now perform different operations according to the amount of power available (for example, when heated to 300 ° C is about 10 seconds at 18W, but about 15 seconds at 12W). Therefore, in order to ensure a better user experience, I decided that the device should provide visual feedback on the display, indicating the voltage and maximum current negotiated with the potential intelligent charger.
I also want to keep the ability to update the product firmware via USB, which means that in addition to using the data cable to induce the resistor or change the voltage level, they can still be used for traditional USB communication.
The currently reserved solution uses the Diodes Incorporated PI3USB9281 charger on the data cable, then the multiplexer, redirect these data lines to the onboard DAC of STM32, for HVDCP negotiation or STM32 onboard USB PHY. Finally, the Anshen Semiconductor FUSB302 Type-C controller for USB power supply.
Since the initial hardware design, I accidentally discovered a number of other proprietary non-standard charging protocols (OnePlus Dash Charge, Oppo Super Vooc, Huawei Supercharge, Motorola TurboPower, Mediatek Pump Express), which seems to have little reverse engineering. If the current hardware design allows, I am sure to add support for these devices through future firmware updates.
The temperature accuracy demonstration of the works of Solder Ninja will be appreciated. Note that the device is powered by a 12W power supply, so the rise time is slow, and the accuracy of the specific temperature can be seen throughout the rise range.
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Copyright statement: HackADAY authorization, Circuit City original translation video, declined!
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