I am using esp8266 with Arduino framework to drive a LED matrix display and some sensors. The problem I encountered is as follows: when I want to read data from CO2 sensor (mhz-19b) I have to do so by sending a command via serial and then read the answer it gives me. This of course takes some time and causes a delay in my code which means the LED matrix display stops refreshing and goes dark for a short but noticable amount of time.
I have a smiliar problem with reading data from DHT22 temperature and humidity sensor (reading data takes some time and causes a delay in code).
Is there anyway I could solve this? Perhaps with some kind of pseudo-multithreading (if that even exists). Also would using esp32 (which is dual core) instead of esp8266 help?
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This is driving me nuts for a couple of days now, so maybe you guys can give me some insights into what is going wrong.
I'm trying to read some data from an EEPROM (24LC16B) with an STM32(F0), but it just doesn't let me. I've tried an Arduino, which worked and does still work, so I do know that the wiring is correct.
This is my function to read the EEPROM data. (It is cut down to the very basis, just for testing): (Pastebin of my I2C_setup function)
uint16_t readEEPROMData(uint16_t deviceAddress, int memAddress){
// Wait while I2C peripheral is not ready
I2C_WaitForFlag(I2C_ISR_BUSY);
// Start I2C write transfer for 2 bytes, do not end transfer (SoftEnd_Mode)
I2C_TransferHandling(I2C1, 0xA2, 2, I2C_SoftEnd_Mode, I2C_Generate_Start_Write);
I2C_WaitForFlag(I2C_ISR_TXIS);
// For testing purpose, be sure to generate a stop command...
I2C_TransferHandling(I2C1, 0xA2, 0, I2C_AutoEnd_Mode, I2C_Generate_Stop);
return I2C_COMM_STATUS;
}
Here's an pastebin of the Arduino library I used.
I've used a logic analyzer to see how the communication is going, and now I really don't understand it. Here's a printscreen of the working Arduino version:
And here's a printscreen of the STM32 communication:
Logic analyzer exports (viewable with Saleae Logic)
As you can see, I'm using the same address (although I had to use 0xA2 with the STM32), and there are no weird things happening, besides the NACK. So what could possible be wrong?
Confirm if all bus timing requirement are satisfied.
Confirm if their is adequate delay after every write cycle (5 mS)
Confirm is bus capacitance falls under permissible limit of I2C (400 pF - Theoretically).
Confirm if the correct VCC is supplied
As mentioned by you are interfacing EEPROM with MCU using cable you need to conform on capacitance.
You can use an oscilloscope to check if their are any distortion in waveform. You can use a LCR meter to check the capacitance.
Try reducing bus speed 25kHz to 50 kHz and check waveform.
Try increasing the strength of pull resister.
The problem with the wrong VCC capacity (4.2v instead of 5v for example) is, that the timing can be different to. (not fully verified, but it fixed the problem)
I am using 6 different sensors which are working simultaneously, but I got a problem in the readings from LM35 temperature sensor and MQ-7 Carbon Monoxide sensor. The values are changing depending on the power source.
How can I fix this problem? I'm planning to use a Sony power bank to feed my system but I am getting the wrong values especially from the temperature sensor.
Make sure that your power source is stable and continuous (i.e. make sure that your power bank is working fine and check its current output if its compatible with Arduino)
Make sure that your sensors are wired correct and working fine, try with different LM35 and MQ-7 sensors, if you have that chance.
Make sure that you are supplying your circuit with correct voltage and current, sensors may work unstable if you are supplying them directly from Arduino pins (because maximum current limit of the pins onboard may not be enough for your circuit), try an external power source such as MB102 power module.
Although, it's not a coding problem my suggestion is you can use signal conditioning to solved this. Search about low pass filter and high pass filter to filtering frequency in output sensor.
The simple method is using voltage divider, like this:
Vout = (R1/R1+R2) * Vin
R1 is your sensor, and R2 is resistor.
Im a PIC fan. I have not used arduino. but I have got a problems when Im going to control servos with pic.
1) when PIc is controlling the servo it cannot do enything else. so during that period it cannot get the sensor readings.
2) after driving the servo to a certain position and now when the pic is doing something else, the pic does not further more generate the pwm signal in the servo connected pin. so the servo may rotate back due to the load.
now my first question is will arduino genarate the pulse continously in the attached pin after the codes
servo s;
s.attach(13);
s.write(120);
or are there eny librarys to control multi servos using PIC in mikroc to avoid the above mentioned problems.
or is it better to use two PICs one to drive servos only and the other for processing and sensor reading, and connect them using I2C.
please I need help from an expert. please reply. thank you...
Yes the Arduino is able to generate the pwm continuously.
Arduino langage is C/C++ with some build in features like analogWrite()for pwm, which make it really easy to program.
Regarding your "when something is running, it can't do anything else" problem, that's one of the major limitation of the Arduino platform as is. You can overcome those limitations by using ISR (Interrupt Service Routine), timers and hardware interrupts.
If you're comfortable with C/C++, you can also use a Real Time Operating System (RTOS) which lets you run think like a regular operating system would: allow cpu time to each task so fast that they seem to run in parallel. But that's not as easy to use as the basic Arduino features, so think carefully if you really need those functions (scheduler, "multi-task", round rubin, etc.)
Hope it helps!
I am planning a similar project, using a PIC16F872, to control a servo motor. I am thinking of using a 32 kHz crystal to have a PWM suitable, of 35Hz and pulse width centred on 1.05 mS. In my case I will first be doing A/D measurements; then when required running the motor. The motor will have a continuous signal until a 'stop' switch gives an interrupt to the PIC.
I should mention that I have modified the servo for continuous running by disconnecting the feedback pot.
I am using the TinyGPS library and am trying to display information to get to a specific latitude/longitude via an LCD screen.
I am not getting any data. The output of directionto is "broke" and distanceto and bearingto is 0.
Code redacted
And here is what my pins/hardware look like: http://i.imgur.com/7iDBwxm.jpg
I am using an Arduino Uno, LCD shield and GPS shield by ITead Studio.
I am hoping it is either the pins or not having a GPS signal.
Reddit post: Arduino TinyGPS help
The baud rate for SoftSerial should be 9600.
You need to debug the system step by step to understand where the problem is.
I would start using only the serial monitor and no display.
Please note that when you switch on a GPS that has been moved for several hundred km, and the same is when you switch it on for the first time, may take a while to get the satellites and start giving out some data. Make sure you are in a open area and wait for 5 to 10 minutes before you declare it as "not working". The next time you will switch it on will be much quicker.
I have checked the documentation of your shield and what they also say is to make sure the Micro SD card you use is support SPI mode but not just the SD mode, also don’t forget to format it into FAT16 , and add a “datalog.txt” file on your card for Arduino to log the information.
Try that and then read the data on the sd card to make sure that is logging.
Come back with the outcome of the above tests and we will try to support you further.
I am using the Wire library to move some data from a shield to the Arduino.
The shield always puts out exactly 36 bytes (GPS device), but the Arduino sees two data transfers that together add up to 36 bytes. Not always the same count in each of the transfers, but always 36 bytes total. The setup() routine is re-run every time the data comes in.
It's as if the library is re-entering the Arduino application and screwing it royally.
Is this possible?
If setUp() is being run every time data comes in (and are you sure about this?) then this means that the Arduino is resetting/restarting for some reason. How are you powering the GPS shield? If it is glitching the power to the Arduino (drawing too much current perhaps) then that could cause a reset. It could also be something with your code using up too much memory. I'd look at the power issue first.
If you are using Wire.available, note that it does not guarantee that it will return the number of bytes sent. You will need to call it repeatedly until it returns zero.
See an example in the Arduino documentation.