Atten Firmware

Atten Firmware UpgradeThis is GREs introduction to the simple scanner made for people with limited programming knowledge. The menus are fairly simple but not all self. YOUYUE 8. 58. D hotair station reverse engineering 1. The YOUYUE 8. 58. D I have in my possession uses an AVR ATmega. TRIAC via an opto isolator. I will not reverse engineer the schematic 1. I dont care for the analog stuff too much, or the HV side of things safety first, but Ill go far enough to treat most of the circuit as a black box and only care for what is directly connected to the ATmega. The Plan So out the ATmega. ATmega. 16. 8. Reading the potentiometer and 2 buttons is just a matter of minutes, translating that into fan speed hopefully using a PWM pin shouldnt take much longer. Then Ill have a go at figuring out how to drive the display. Once all of the UI stuff works, Ill look into reading the temperature sensor presumably using another ADC input. Calibration and tweaking will be done later. Then Ill very very carefully look into driving the heater probably with PID control. Will I have to deal with zero crossing detection, Ill find outIf all of the standard features work, I might look into adding useful extras a fan test would be nice. A non intrusive way to do this would be to turn turn on the fan at low speed, then the heater for a second or two and check for a temperature increase. If no temperature rise is detected, either the fan or the heater are broken not connected. Step 1 DC power a lot of guesswork. The power supply part fan mcu was pretty easy to figure out. A couple of diodes 7. Atten Firmware File' title='Atten Firmware File' />The two switches directly connect to two AVR GPIO pins and pull them down to GND as expected. Please note that some capacitors etc. It just covers the bare minimum to understand how it works. It seems the air speed is not directly controlled by a PWM pin sadly. The fan itself is switched by a TIP1. NPN darlington, which is used as a high side switch why. There are quite a lot of SOT2. Maybe theyre used to supply the base with a higher voltage It is also strange that some capacitors are rated at 3. V, although the rectified AC for the fan is about 3. V. The fan itself is rated for 2. VDC. Hmmmm. There are way too many small parts next to the TIP1. Ill have to investigate further. Maybe it does monitor the fan current I have a feeling this will take more time than expected. So for now Ill turn my attention towards getting the 7 segment display working. That should be doable in a day. Step 2 7 segment display. The common anode 7 segment display is directly driven by the MCU. Three GPIO pins are dedicated as current sources to activate each of the three digits, relying on persistence of vision for a steady display. Another 8 GPIO are used to drive the 7 segments plus the decimal points just one is used. The 7 segment pins are PB0 7 seg digit 1. PB7 7 seg digit 2. PB6 7 seg digit 3. PD0 7 seg top. PD1 7 seg bottom left. PD2 7 seg bottom. PD3 7 seg top left. G416VEQrWZM/hqdefault.jpg' alt='Atten Firmware' title='Atten Firmware' />PD4 7 seg dot. PD5 7 seg bottom right. Software For Robotics. PD6 7 seg middle. PD7 7 seg top right. Datasheet SM3. 10. K note pin in datasheet 15 71. Home of all FTA receivers and Bin files Linkbox, DreamLink, Limsat, Jynxbox, IPTV, Pinwheel, Sonicview, Kodi, nFusion, XFTA, IKS Private Servers news. Step 3 Buttons reed switch. Step 4 Fan control. The MCU can stop the fan by pulling the base of the power transistor TIP1. This is done with the help of a small SOT2. PC3. The MCU can also measure the emitter voltage via PC5 ADC5 pin 2. TIP1. 22, most likely to detect fan issues no fan stall. I will have to verify that. R4 and Z1 form a crude reference voltage generator. Together with U7, this forms a comparator of sorts. When the TIP1. 22 is on pull up resistor R5, C7 gets charged to a voltage set by the potentiometer which is derived from the 1. As long as that voltage is higher than the Zener voltage of Z1 plus one base emitter drop of about 0. V of U7, U7 turns on and reduces the base current of the TIP1. The fans slows down. This forms a basic speed control mechanism for the fan. At first I thought this circuit would oscillate, but I was mislead by the zener diode U7 comparator. If you forget about Z1 etc, this is just a simple current limiter. If U7s VBE voltage is too high, too much voltage drop across the load, it turns on and tames the power transistor. They could easily have driven the fan directly from the MCU, but maybe they wanted to make sure the fan always runs, just in case the MCU locks up. However, hardware PWM is very reliable and the MCU drives the TRIAC as well. Who knowsStep 5 Heater control ON OFFStep 6 A mystery. Step 7 FIRST LIGHTWhat works so far displayreading the 2 buttonsreading the wand sensor reed contactfan ON OFF overridecrude heater control just ON OFFTodo read the thermo couple voltage from the OP 7 implement a control loop for the temperature most likely PID sensible calibrationread the fan status signal not quite sure what it isContinue reading Part II.