[Solved] Program Pro Mini w/ usb serial dongle?

Projects Programming
1

I just started fooling around with Arduino, i bought a duemilanove and i have a pro mini coming in the mail.
Well anyway, i was wondering if anyone knew if it was safe to program the pro mini using a standalone USB-to-Serial dongle? All it does is plug into usb and give me a serial port (since iMacs don't come with serial ports -_-)

Ipopped the dongle open and it has the same FT232RL chip found in the duemilanove with the addition of another chip we cant identify.
All i really know is that the mac drivers that come with the Arduino app make the dongle usable for me again :stuck_out_tongue:

Thanks and sorry if this isn't exactly the right place to put this but i figure programming

2

It should work, but there is one issue. Is your pro mini 3.3v or 5v logic level? If it is 3, there is a possibility that the dongle is 5, and that would fry your pro mini. If it is 5, it will work fine, because even if the dongle were 3, a 3.3 would still register as a logic high.

3

Second issue is that some of those 'serial dongles' output true RS-232 voltages (+12 to -12vdc) which would destroy arduino serial pins, and that might be what the second chip does, create rs-232 voltages. You must have one that has TTL serial voltage outputs, and yes check if it uses 3.3 or 5 vdc signals and don't use 5vdc signals on a 3.3 volt arduino board.

Also most serial USB cables don't support the DTR signal so the auto-reset function for uploading won't work and you will have to learn how to time manual reset switch when uploading from the IDE.

Lefty

4

But unless the other unidentified chip is a max 232, doesnt the ft232 work at TTL levels only?

5

To clarify, the pro mini is the 5v version

I still can't find anything on that second chip except that it has the same number of pins as the ft232

Before my pro comes in I'll build a little test rig using a dsub cOnnector and see what voltages really come out of it. I was originally using the USB to serial to interface with my x10 modules throughout the house.

If I can I'll post some pictures of the board if I can get enough focus

6

Are there no markings at all on the other chip? How is the other chip connected to the FT232 and the DSub connector?

7

USB to Serial - No. The serial Tx line to your Promini's RX line will swing at least +/-3V, the -3V will damage the pin.
You will need an additional RS232 to TTL converter to get 0-5V output to the Rx line.
such as
http://www.nkcelectronics.com/rs232-to-ttl-converter-board-33v232335.html

(or this with a female-female or male-male adapter
http://www.nkcelectronics.com/RS232-to-TTL-converter-board-33V-to-5V-Wrong-DB9-male-adapter_p_259.html)

8

Or get the proper USB-TTL adapter that combines both, has 6 pin connector to go onto the Promini connector, and also controls the DTR line

http://www.nkcelectronics.com/ftdi-basic-breakout.html

9

If the USB-Serial adapter is not TTL, just use your arduino duemalinove to program the promini.

10

bilbo,
How you would you suggest doing that? Pop out the DIP328, connect the promini Rx/Tx/Reset/Power/Gnd pins to the same on the duemilanove headers?

11

While that would work, I would think that you would not need to remove the atmega chip as long as you bypassed the auto reset as seen here: Arduino Playground - DisablingAutoResetOnSerialConnection

12

Thats what i figured... but since i already had the USB-to-Serial thing laying around i thought i'd ask.
so i might as well buy the FTDI bored like a normal person :stuck_out_tongue:

at bilbo,
so do you mean hook up the pro mini to in essence piggyback off the serial lines going to the duemalinove and temporarily disable auto reset on the duemalinove so it doesn't try to load the sketch I'm intending to send to the pro?

for those interested and as promised, heres that the thing looks like :confused:

Uploaded with ImageShack.us

13

Just as an aside, in my experience 3.3V Pro-Mini boards can be programmed just fine at 5V. The voltage regulator doesn't seem to mind the excess voltage applied to its output. Of course you have to be more careful if anything else is wired into the Pro-Mini's outputs.

14

@tim7,
what device did you connect it to, to get it to your computer?

15

Just an ordinary FTDI-cable or FTDI "basic" adapter, which applies 5V power on the output-side of the Pro-Mini's voltage regulator. For this to be ok, there must not be any power in the input-side of the regulator (the "RAW" pin).

16

Shippo, that is what I mean, and it works very well. The arduino already has an ftdi, so why buy another?

17

The Promini does not have an FTDI. Just the TTL lines that the FTDI connects to.

18

@CrossRoads
I think he means the duemalinove has ftdi so use that to connect the promini

19

Sorry for being unclear, that is what I mean. Buying another ftdi makes no sense when you already have one in the duemalinove .

20

Ah, yes, too much involvement in too many threads I guess.
I modified my Duemilanove with 4 pins at the X3 connector & bootloaded parts with this method:
http://www.geocities.jp/arduino_diecimila/bootloader/index_en.html