Operator conditions like light, temperature, water, dust and vibration are a rich source for constraints and qualities of a system architecture. They affect the SoC, display and connector selection, the touch gesture recognition, the communication between system components, the cabling, the use of a window manager and more.
Read More »Architecture of Qt Embedded Systems: Operating ConditionsIn the first post of the Speaking CAN series, we learned how the terminal sends a read-parameter request to the ECU and how the ECU sends a response with the value of the parameter back to the terminal. This works fine, as long as the terminal does not send too many requests too fast.
We set the size txqueuelen of the write or TX buffer to 10, which is the default for many Yocto-based Linux systems. If the terminal writes, say, 50 requests to the CAN bus without any pause, we’ll see several error messages No buffer space available in the log window of the terminal. The terminal caused an overflow of the write buffer in the CAN controller.
If we have a request-and-response scenario, the terminal can wait for the response, before it sends the next request. If the response does not arrive within a certain time, the terminal flags an error.
Avoiding a write buffer overflow becomes more difficult, if the terminal sends out messages without expecting a response or if the terminal expects a response only every, say, 200 messages (e.g., an acknowledgement how many messages the ECU has received). The solution is to configure the CAN controller of the terminal to receive its own messages.
Read More »Speaking CAN: Write Buffer OverflowAgricultural OEM Krone bets on Qt software library for development of their terminal / First prototype read in less than three months
585 horsepower, 15.6 litres engine displacement and an up to 9 metre wide cutterhead – forage harvesters are among the most powerful agricultural machines. It takes a lot more technology and know-how to drive such a vehicle than a car. The driver terminal of a forage harvester must process information from more than 30 components like motor, cutterhead, metal detector or grinder within tenths of a second. The terminal additionally provides a diagnosis system. The agricultural OEM Krone from Lower Saxony has built all these functions into the touch-screen terminal of its forage harvester Big X 480/580. The HMI software of the terminal was developed with the GUI and application library Qt.
Read More »Revolutionary HMI-Design of Forage Harvester