Hello, i would like to present my Smart Life challenge idea.
I am thinking about making reflow oven. It will have 3.7 inch capacitive touchscreen with 800x480 AMOLED or SLCD screen for user interace as well as encoder for setting up time and temperatures of each reflow process steps. (maybe i will going to use unipolar stepper for this function, since it has very positive feedback, and very long life span )
PSoC4/5 will run control algorithms for heating, and so on. I will use two K type thermocouples for temperature measurement ( maybe one will be glued to small pcb with only copper and solder mask to get idea about this arrangement temperature, and also maybe second thermocouple will be glued to small FR4 board, to get idea about pcb temperature without any copper around.So i could guess temperature of pcb. It will get all commands for GUI controller ( for now i am thinking about STM32F429isince i need lot of power to drive large 800x480 screen and at the same time get information from touchscreen
And third large part will be SMPS for heating. Since i want to get precise temperature control, i will use PWM control for heaters. I don't want to use SCR , or even relay, since it can produce high temperature fluctuations.
Ok so first job was to reverse engineer HTC desire screen. that take me some time, but i finally get it working, so now i can produce similar user experience as any high end smartphone can give for users. I will share code and pin-out, so others can try this out ( as well as where to get connectors, since it nonstandard 10 pin 0,4mm pitch small size board to board connector)
Still have many problems with AMOLED screen. It has not only RGB565 interface but also SPI interface for seting up screen, and at this time i don't know exact registers and data. but at least, i getit display something. This part will be hardest in this project
Now comes easy part, making 2000-3000W PWM controller for heater. For now i am thinking about PWM controller driving high power IGBT transistor, and all data will come via Analog ISO digital I2C or simple isolator, since i don't want to have common ground that is directly connected to heater ground. So i will have to separate power supply, one for driver electronics, one for heater control electronics, simple .
YES, get AMOLED panel working with my user interface controller. That was very very hard, but result is superb. I guess that would be oven with best display in the market
Only problem is that screen is 800x480, i will try to get resolution cut by half of each axis (240x400 would be tip top but i will have to add small fpga fr it, bummer )
wow, quality compared to other screens are just mind boggling
mini IR oven for my project. Its 800W and it has nice flat side for touchscreen mounting. Problem is, it will "just fit" with not much place around.
Also, all markings will be removed, and if all goes well, i have access to laser engraver for some custom markings ( in university we have laser marking machine ). Biggest problem is that i have very little room for my PWM controller, 12v power supply and my driver. I bet i have to integrate all electronics on single pcb and also send it to OHS Park for manufacturing, so not much time to spear
Heater power control
As you might know,i will use PWM control, so i can adjust heating power , and by doing that i should get better temperature control ( low temperature "ringing" with flat temperature profile )
Idea is this. PSoC 5 will generate PWM signal by measuring temperature from sensors, and adjusting pulse width according to PID controller state. Set point will be controlled by STM32F429 via UART. At start-up, PSoC will check if driver has ULVO, if yes, displays error, since i can't run power mosfet with gate voltage below 10V. Temperature fault will not be used, since i have 100mOhms MOSFET and rms current is just 5A, that is very little of heat. ( maybe i will add more heaters to get faster heating curve, but for now original heaters will work just fine.
Hrr, is is very hard to make nice looking front panel. I have no room for any mountings, also very little room for AMOLED itself.
Plan is to use FR4 sheets, cut it with cnc, and glue them . For now it's my only option
If some one still has a question, do i really need stm32f429i, here is the answer : (still, it's only for basic functions, more pins will be used in this design )
Still lot of work to be done.