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9

The 'n' is meant to be a placeholder for the actual UART peripheral that you want to use when discussing the set of registers associated with the UARTs. So if you had two UARTs, you could read the status register from the first UART by replacing it with a '0' or the second UART with a '1' like: UCSR0A or UCSR1A - note that these two are #define'd for you in ...


5

I need to connect this module to a third party system that only accept RS232 with -12V / +12V signals levels. You will need to supply details of that device, and a copy of the documentation which leads to the conclusion that it requires those signal levels. That requirement is not part of RS-232. When viewing MAX3232CAE TX pin trace with an oscilloscope, ...


5

Just solved this overheating problem on a batch of max232 chips using a couple of resistors. See the input pins 10 and 11 http://www.maximintegrated.com/en/products/interface/transceivers/MAX232.html and click the picture to enlarge. There are supposed to be 400k resistors internally but measuring the resistance to pin 16, I got 40 megohms on this batch. So ...


4

I think you are confused about the voltage level used to power the camera and the voltages used to communicate with the camera. The fact that the camera is powered with +5V from the Arduino is really irrelevant in this case. If the camera has a true RS-232 interface then a logic 1 is represented by a voltage more negative than -3V and a logic 0 is ...


4

I have used these 10 x 15mm converter modules from AliExpress for more than 3 years now, probably around one hundred of them. Just recently, on my last 20 or so circuits, I stumbled on this fire hazard issue. I used all the advice I could gather from different forums and I want to share my full recipe in the order I tried them because I reached a really ...


3

I would guess that it could be lack of supply stiffness with the MAX device. Are the pump caps 0.1 uF as shown. And what cap is on the 3V3 rail and how far away is it from the IC. If the power supply is not stiff enough either because the "pump" lacks energy or the source rail is noisy then something like you are seeing could happen. Pin 2 and pin ...


2

I had this issue too. Was using 1uf tantalum polarized capacitors. If I unplugged the power while leaving serial attached, then reattaching power, pin 6, the negative voltage source, would go positive ~1v. The chip would heat up and stop working. For whatever reason, adding a couple .1uf ceramic capacitors for decoupling, in addition to what it called ...


2

The RS422 and RS485 standards only specify the electrical requirements. Both can be full-duplex but isn't a requirement of either specification. They are also similar enough that you can interoperate them in some situations. Now the big difference, which you already noted is that RS485 uses a tri-state system. This means you can have multiple transmitters ...


1

100 ohm twisted pair is a poor match for rs232 drivers (which are about 1000 ohms) , the main limitation is the drivers capability to charge and discharge the line. In my experience on long runs the main problem is dielectric absorbtion during the idle time causing the start bit to be distorted, this can be mitigated somewhat by fitting a diode at the ...


1

Answer has been given by Eminem, see his comments below: Eminem I use the MAX232, and 4 0.1milifarad ceramic capacitors. It works fine for my uses. Me In the datasheet in figure 4. You have to put 8.5V on the 2 and 6 pins. Is this necessary? And do I need a logic level controller between the converter (attached to the µ-controller, 5V) and receiver (3.3V)...


1

For my application I couldn't lower the power rail to 3.3V as suggested by one of the posters, as I was powering a device using the RTS/DTR pins which needed a higher voltage than the chip was producing at 3.3V. I ended up using 10K pull-ups on the inputs plus 50 ohm in series with VCC and that solved the problem for me, while keeping the output voltage ...


1

If you mean connecting the AVR pins directly to a MAX3232 found at the camera side then you should avoid it because the (MAX3232) Tx pins transmits signals in a range of +5.5v to -5.5V that are not safe for the AVR. Just use a max3232 in the AVR side too.


1

Definitely sounds like a timing issue. I think your clock is running too fast and instead of bit 7 being sampled, the following stop bit (HIGH) is shifted into the shift register.


1

When I see the "variables in this function are undeclared" message, it often means that I haven't included or linked some library I'm trying to use -- in this case, I perhaps the library that defines TXEN0, RXEN0, UCSR0A, UBRR0H, etc. There seem to be two popular ways to implement serial communication with the ATmega328: "Low-level control" using the gcc ...


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