I'm working with a driver board which communicates with a PC program via USB -> FTDI -> TX/RX into the microcontroller. The serial pins are not broken out on the board and I need to talk to the board from another microcontroller (like Arduino). My plan is to just solder directly to the RX/TX pins on the microcontroller despite the fact that the FTDI is powered on and RX/TX of the FTDI will be electrically connected to those pins. I will not be transmitting anything via USB. My assumption is that the FTDI chip will be passive and I can just drive those pins from my Arduino.
Will this cause me any issues? I'm just concerned if the FTDI passively drives those pins low or high, I'll get "smoke" if I follow through with my plan. Perhaps I should put some resistors on my Arduino's RX/TX just as a safeguard.
It's very possible some of my logic is flawed here. Thanks in advance for your advice!!
Cheers
You need to check with the particular FTDI chip you're using on that board.
Some FTDI chips support RS485 and because of the required multidrop capability they operate as open-drain allowing to connect multiple devices.
Even if this solves your hardware problem, you still need to consider how the (live) FTDI chip may respond to your 'unexpected' incoming (RX) data stream. For example, possible XON/XOFF flow control appearing on TX especially since there won't be a consumer from the PC side and the internal FTDI buffers will eventually fill up.
Related
I have ATMEL ICE C initial connection problems - it cannot read device signature, because of the target board voltage isn't between range of 1.8 to 5.5V. It has measured by the Atmel Studio as 1.3V (when target board is powered by the USB connector) or 0.3V (when USB disconnected from target).
It'a a brand new device, and i never used it before, may be i did something wrong?
I had used before AVR ISP handmade by myself, and had used previously programmed target board for this experiment, to avoid possibility, that board is dead. The target is works and blinking heart beat.
What i has done -
1.Connect the target board to the ICE programmer.
2.power target board by USB.
3.power programmer by USB from PC USB port.
4.open "device programming" tab in AS 7.
5.Make all settings for my chip atmega328p
6.press "apply" then 'read'
7.get err msg that voltage is too low.
(while i had measured it directly, by the digital voltmeter on pins +5V and GND on target
board, it's about 4.5V, same as in ISP connector - measured on 2 and
6 pins.)
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#markus-nm where did you take your measurements?
i had measured on pin 2 and 6 of ISP connector and between pin +5V and GND on Arduino Nano board.
What reference was used?
i had used GND pin on target board for the reference.
Did you use the same USB Host for ISP and power?
no, power to target board was from the wall socket USB charger, AND power to Atmel ICE is from personal computer.
If not, did you connect the grounds?
no, but i guess that grounds are already connected on the target board.
Some links to your chip, your board and ISP would be helpful.
ATMEL-ICE-C https://www.microchip.com/en-us/development-tool/ATATMEL-ICE
ARDUINO NANO PRO https://store.arduino.cc/products/arduino-nano
If it's a custom PCB, provide some schematics. Show a wiring diagram of what you did.
no, i had used the standard Nano board (may be not original, but clone, but it is definitely working now, because it can be programmed by the AVRDUDE program and work.)
The Atmel-ICE, by design, has a lot of different ways to hook up the programming connector. Often when I see problems like this it's because the wrong connector is used. Keep in mind the programmer itself has both an AVR and a SAM port. For the Arduino Nano Pro, make sure it's plugged into the AVR port. After that, ensure you're using the correct programming connector on the adapter board that comes with the Atmel-ICE and that it's oriented correctly on the Nano's header.
If that all fails then something is broken.
Will FTDI always converts the data into serial or any other types of transfers?
Will FTDI always converts the data into serial or any other types of
transfers?
Answer to your question in short. FTDI chips implements USB protocol stack that is serial.
The FTDI cable is a USB to Serial (TTL level) converter which allows for a simple way to connect TTL interface devices to USB. The VCC pins of this FTDI cable are configured to operate at 5V with 3.3V I/O.
What happens inside the USB?
USB micro controller inside which talks a proprietary protocol over USB (hence the need for drivers) and converts that into "normal" UART signals and back again.
I have the Arduino UNO board and I want to know if it is possible to use both the USB connection (for exchanging data) and the external jack to power supply it.
I will use the following cable: http://ecx.images-amazon.com/images/I/41OMXaj5cPL.SY355.jpg with a AC-DC 5V adaptor in order to power supply the Arduino. However, I want to use also the USB connection in order to send some data from the computer.
Both will be connected at the same time.
In short, I want the Arduino to be able to run even if the computer is OFF and whenever I open the computer to send data to Arduino from USB connection.
Is this possible? Will the Arduino Uno board support it?
Yes. From the official Arduino website:
Power
The Arduino Uno can be powered via the USB connection or with an external power supply. The power source is selected automatically.
External DC power will override USB power if the Arduino detects it. [Source]
as other said, it is absolutely possible to have both usb and power jack plugged in.
but be aware that if you shut down your computer and turn it on after, when reading the usb port you'll restart the Arduino and might loose important data.
yeah both of them can be used. If you want to upload the code in arduino then simply use the usb cable otherwise keep it on adapter. it wont harm the device.
What I personally do is, I keep on plugging the adapter and remove the usb once I am done with uploading and then test it as normally the usb cable is quite small and I normally work on robots so I need long wires.
if you want just plugs it in, it's ok but Arduino board will chose one and usb has priority to other power source.
********* Very important :*****
if you are controlling other circuits, that are connected to an external power supply, with your Arduino and connecting it to your PC's usb, Arduino will have potential difference and it will cause current flow that will damage your PC and Arduino board. if you want to do such thing, you have to shield your Arduino board from your other circuits that you want to control and they have external power source. this could happen with optocouplers for digital ports, non signal analog ports with shield relays, and complex analog circuits for analog signals
I have an Arduino 2560 and would like to send serial data to my PC. However, I am currently not using the Arduino Bootloader because I wanted to use a program that I wrote for an Atmega644 before (as far as I understood, one has to use the Arduino language when using the Bootloader?).
Does anyone know if what I am trying to do is possible with reasonable effort?
Connection to PC via 2560's serial0 does not depend on bootloader (if you plan connection when main program is running). You need 16u2 running to bridge 5V serial UART to USB or you can of course use any other option (e.g. MAX232 or so) to convert 5V UART to USB or RS232. But in case of RS232 double check baud rate error because of 16MHz crystal for particular baudrate.
2560 bootloader just implements firmware flash.
I just start a project which is very basic actually. But I need an information. It is about arduino serial communication. Here is the question.
If I connect arduino to computer using TTL to RS232 converter without USB cable then can I still use serial monitor to get some data or what happens ? Assume arduino is programmed before using usb cable, and it is powered externally when usb is not used.
for instance the code just
Serial.println("It is working");
delay(1000);
Thansk a lot.
you will fry it. Standard RS232 use a +-12V level, while arduino use TTL level (0-5V), so you still need a RS232 -> RS232TTL converter. If you use it, then using virtual serial over USB or real hardware serial is exactly the same, except that hardware serial port never appear/disappear when you plug in the arduino (there is not something like plug'n'play in rs232, it is always plugged)