Go Down

Topic: Atmega328P TQFP32 (Read 1 time) previous topic - next topic

tack

What I meant is that you can find some of these modules on eBay where they have been modified with the series cap on the correct line. Those ones will do the auto reset of the ATMega without the need to add the series cap on the board itself.

Paul__B


What I meant is that you can find some of these modules on eBay where they have been modified with the series cap on the correct line. Those ones will do the auto reset of the ATMega without the need to add the series cap on the board itself.


I am not aware of a USB to TTL module - on eBay at least - which has been modified especially to incorporate a series capacitor for use only with breadboarded ATMegas, making it non-standard as an RS-232 interface.

I understand some have now been made with the corrected wiring and a pinout to match the FTDI module which does not contain such a capacitor in order that they do suit the Pro Mini and other ready-made boards all of which have the capacitor on the MCU board itself.

Can you point me to an example of such?

tack

#17
Sep 22, 2013, 12:05 pm Last Edit: Sep 22, 2013, 12:11 pm by tack Reason: 1


I am not aware of a USB to TTL module - on eBay at least - which has been modified especially to incorporate a series capacitor for use only with breadboarded ATMegas, making it non-standard as an RS-232 interface.

I understand some have now been made with the corrected wiring and a pinout to match the FTDI module which does not contain such a capacitor in order that they do suit the Pro Mini and other ready-made boards all of which have the capacitor on the MCU board itself.


Must say that the use of all those italics and stating you are not aware, does make it come across as a little condescending; i.e. you're not aware, therefore I'm making something up.

Quote from: Paul_B

Can you point me to an example of such?


Of course,

http://www.ebay.co.uk/itm/USB-TTL-to-Serial-Converter-Module-CP2102-AUTO-RESET-ENABLED-for-Arduino-Project-/321112731162?pt=UK_Computing_Other_Computing_Networking&hash=item4ac3cf6e1a

Paul__B


Must say that the use of all those italics and stating you are not aware, does make it come across as a little condescending; i.e. you're not aware, therefore I'm making something up.

Well, I am just pointing out the need for clarification.  My italics are to point out a specific reference to breadboarded, "home brew" versions of the Arduino concept.


Quote from: Paul_B

Can you point me to an example of such?

Of course,
http://www.ebay.co.uk/itm/USB-TTL-to-Serial-Converter-Module-CP2102-AUTO-RESET-ENABLED-for-Arduino-Project-/321112731162?pt=UK_Computing_Other_Computing_Networking&hash=item4ac3cf6e1a


OK, so I would really like to confirm that you have purchased one of these and observed that it actually has an 0.1µF capacitor added (because I cannot see why it would)?

While that site certainly goes to great length and font size to stress that it is "Auto-Reset Ready" - and presumably is in the sense that it will emulate the FTDI module, since it does not mention such a capacitor and since the capacitor would only be required to be added for "breadboard" and possibly some of the Adafruit variants, I am naturally inclined to presume that it would not.

If we can comprehensively  verify this one way or the other, then all of us can give more useful advice in future.

tack

#19
Sep 22, 2013, 02:21 pm Last Edit: Sep 22, 2013, 02:27 pm by tack Reason: 1
Jeesh, you are hard to convince!

Yes, I've bought one before. Yes, it has been modified to include the 0.1uF cap to provide a direct AVR reset pulse on a pin from the module. As it clearly states, it will work with 'barebones' set ups without the need to do the manual reset.

Paul__B


Jeesh, you are hard to convince!

Yes, of course I am!  I am very curious as to just what is going on here.


Yes, it has been modified to include the 0.1uF cap to provide a direct AVR reset pulse on a pin from the module. As it clearly states, it will work with 'barebones' set ups without the need to do the manual reset.

The module you cite is fascinating, since according to the illustrations, it has no visible differences to the one the same seller is offering (for a somewhat lower price) apart from what appears to be a label declaring "AUTO-RESET-READY" stuck over the four terminations for DTR, DSR, RTS, CTS.  No such capacitor visible.

Am I to therefore to gather (since the opposite side of the board is not revealed) that he has modified these by cutting the track to the reset pin on the CP2102 and wired this extra capacitor on the back of the board between DTR and the "RST" pinout?

tack


Am I to therefore to gather (since the opposite side of the board is not revealed) that he has modified these by cutting the track to the reset pin on the CP2102 and wired this extra capacitor on the back of the board between DTR and the "RST" pinout?


Yes.

Paul__B

#22
Sep 23, 2013, 04:04 am Last Edit: Sep 23, 2013, 11:45 am by Paul__B Reason: 1
Right.  Well, that's interesting, but the process of getting a full description of what is happening here seems to have resembled pulling teeth.

I am still wondering whether any other vendors are offering a similarly modified board.  I do notice that one of my favourite vendors is offering a board with the "RST" fault corrected - and stating such, but not with a capacitor added.

My original point was just that - since Arduino boards as such incorporate the capacitor in the design, it is sufficient simply to provide an accurate emulation of the FTDI interface for which they were originally intended.

Go Up