TTL adaptor :

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Spildit
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TTL adaptor :

Postby Spildit » Thu Apr 25, 2013 12:26 am

Diagram for building the RS-232 TTL COM adaptor :
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Re: TTL adaptor :

Postby aut0 » Thu Apr 25, 2013 9:43 am


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Re: TTL adaptor :

Postby Spildit » Tue May 21, 2013 12:10 am

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Re: TTL adaptor :

Postby fzabkar » Tue May 21, 2013 8:45 am

Some newer drives have I/O voltages of 2.5V rather than 3.3V. The MAX232 IC runs from a 5V supply and requires that high level input voltages exceed 2V in order for them to be properly detected as highs. That's something that you need to watch out for.

I use the MAX3232 which can run from either a 3.3V supply or 5.0V. The high threshold is 2.0V for a 3.3V supply, and 2.4V for a 5V supply. Therefore my circuit is likely to be unreliable at 5V if the HDD has a 2.5V Vio.

http://datasheets.maximintegrated.com/e ... AX3241.pdf
http://www.ti.com/lit/ds/symlink/max232.pdf

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Re: TTL adaptor :

Postby flydr4g0n » Mon Jul 08, 2013 4:20 am

fzabkar wrote:Some newer drives have I/O voltages of 2.5V rather than 3.3V. The MAX232 IC runs from a 5V supply and requires that high level input voltages exceed 2V in order for them to be properly detected as highs. That's something that you need to watch out for.

I use the MAX3232 which can run from either a 3.3V supply or 5.0V. The high threshold is 2.0V for a 3.3V supply, and 2.4V for a 5V supply. Therefore my circuit is likely to be unreliable at 5V if the HDD has a 2.5V Vio.

http://datasheets.maximintegrated.com/e ... AX3241.pdf
http://www.ti.com/lit/ds/symlink/max232.pdf


The max VCC in for MAX3232 is +6V maybe at 5.5 or 5.4 V supply rate high threshold is 2,5V :?:

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Re: TTL adaptor :

Postby fzabkar » Tue Jul 09, 2013 9:07 am

According to the datasheet, a 1.7V (= 5V - 3.3V) variation in the supply voltage results in an 0.4V difference in the logic hi threshold. I agree that an increase of 0.5V in the supply might reasonably be expected to raise the logic hi threshold by 0.1V. In fact this was a troubleshooting technique that I used in the past to locate intermittent faults in digital logic. It also works the other way, too. That is, lowering the supply voltage can sometimes expose a latent fault.

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Re: TTL adaptor :

Postby Spildit » Tue Jul 09, 2013 3:15 pm

fzabkar wrote:According to the datasheet, a 1.7V (= 5V - 3.3V) variation in the supply voltage results in an 0.4V difference in the logic hi threshold. I agree that an increase of 0.5V in the supply might reasonably be expected to raise the logic hi threshold by 0.1V. In fact this was a troubleshooting technique that I used in the past to locate intermittent faults in digital logic. It also works the other way, too. That is, lowering the supply voltage can sometimes expose a latent fault.


Thanks for the clarification :)
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Re: TTL adaptor :

Postby fzabkar » Wed Nov 06, 2013 10:34 pm

After seeing some problems in other forums with certain adapters, I did some digging and discovered that the newer drives have lower I/O voltages, which means that they cannot communicate with earlier USB-serial bridge chips.

Therefore I would start by measuring the voltages at the drive's jumper pins. That should tell you the signal levels. I would also measure the voltages at the adapter's I/O pins.

Some PL2303 devices appear to have problems with the latest drives, apparently because their signal outputs are in the 0V - 2.0V range. There was a recent thread at HDD Guru where someone needed to do some minor hacking to get his adapter to work.

http://forum.hddguru.com/viewtopic.php?f=1&t=26917

That said, others have used the same Prolific chip with success, although their drives may have been earlier models, or they may have been using the latest version of the chip.

A further complication is that Prolific's PL2303 chip has been copied, so you won't know which version you have.

According to the following datasheets, the "D" version of the PL-2303HX controller can connect with 1.8V I/O devices, but the earlier versions are limited to 5V and 3.3V I/O:

http://www.prolific.com.tw/UserFiles/fi ... v1_4_4.pdf
http://www.stkaiser.de/anleitung/files/PL2303.pdf (early version)

The CP2102 is limited to 3.3V I/O whereas the CP2104 can handle 1.8V and above:

http://www.silabs.com/Support%20Documen ... 2102-9.pdf
https://www.silabs.com/Support%20Docume ... cp2104.pdf

ISTM that the best adapter would be one where you could select the I/O voltage -- 1.8V, 2.5V, 3.3V, or 5V. For maximum compatibility, avoid the CP2102 and early versions of the PL-2303. Instead I would recommend either the CP2104 or the PL-2303HXD.

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Re: TTL adaptor :

Postby HaQue » Fri Nov 08, 2013 10:14 am

Thanks a lot, a good overview of the different adapter chipsets is extremely helpful. cheers

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Kindle serial adapter level shifter circuit

Postby fzabkar » Sun Oct 05, 2014 9:05 pm

"Aesebu" at HDD Guru kindly alerted me to the following "Kindle serial adapter level shifter circuit":
http://farm8.staticflickr.com/7011/6583 ... ff44_z.jpg

228167mod18V.jpg


It is discussed by "geekmaster" in this thread:
http://www.mobileread.com/forums/archiv ... 62775.html

Here is aesebu's implementation:
http://img15.hostingpics.net/pics/217313dku518.jpg

The adapter enables an HDD with 1.8V I/O to interface to an LVTTL adapter with 3.3V I/O. Simply speaking, the level shifter converts a 0V-1.8V output range to an 0.6V-2.4V input range. It does this by way of a diode (1N4148) and a resistor.

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Re: TTL adaptor :

Postby samsam » Tue Dec 30, 2014 9:56 am

Hello,

I read this post and I want buy an ebay TTL adaptor.
First : usb or serial ?
(all the software was able to work with com3 or com4 ?)

Second : (specially for fzabkar )
you say
newer drives have I/O voltages of 2.5V rather than 3.3V. The MAX232 IC runs from a 5V supply and requires that high level input voltages exceed 2V in order for them to be properly detected as highs. That's something that you need to watch out for.


that is to say new ebay converter doesn't work ?
On the picture how to see if it could work (or not) ?
sorry if I made bad reading of your post.

Thanks

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Re: TTL adaptor :

Postby Spildit » Tue Dec 30, 2014 8:38 pm

Hi there !

If your computer have a serial port you can consider buying the serial port version (like I have) but the majority of people would go for a USB one. The USB have the disadvantage of needing a driver (normally supplied with the adaptor).

The eBay adaptors will work, just be aware that *some* adaptors might not properly work with some newest drives.

Regards.
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Re: TTL adaptor :

Postby Vipersz » Fri Jan 02, 2015 8:24 pm

Hello, i can use this http://radio-magazin.shopmania.biz/cump ... sb-7073570 adapter for viewtopic.php?f=83&t=874 this procedure?

If i can't use, can you recomand one with is fully operational with my procedure? thanks.

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Re: TTL adaptor :

Postby Spildit » Fri Jan 02, 2015 8:38 pm

Vipersz wrote:Hello, i can use this http://radio-magazin.shopmania.biz/cump ... sb-7073570 adapter for viewtopic.php?f=83&t=874 this procedure?

If i can't use, can you recomand one with is fully operational with my procedure? thanks.


Hi there !

The adaptor that you listed should work without any issue.

Regards.
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HELP ME, SEAGATE 7200.12 ERROR BAD

Postby ttc2010 » Sat May 30, 2015 6:36 am

Untitled.png
NOT REPAIR HDD, ERROR NO REPAIR ,MOVE BAD TO P-LIST ?, FORMAT V-LIST ERROR, HELP ME, THANKS


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