user7531: I recently bought an Arduino Pro Mini(3.3V 328p, 8MHz) along with a CP2102 USB to TTL UART convertor. When I try to upload a sketch to the Pro Mini using it, I get a avrdude:stk500_recv(): programmer is not responding error. My connection was like 
Arduino pro mini                CP2102
TXO  ----------------------------> TXD
RXI  ----------------------------> RXD
VCC  ----------------------------> 3V3
GND  ----------------------------> GND
DTR  ----------------------------> DTR

I tried inter-connecting the TXO and RXI pins and had no luck. Also pressing and releasing the reset button on the Pro Mini doesn't seem to work either.  I also tried programming it with my Arduino Uno, by removing the 328 and connecting correspondingly. Still no use. 
Does any one have any ideas?

user14843: In the Arduino IDE for my Pro Mini I have to select the board: 
"Arduino Deumilanove or Diecimila"
I'm not sure why this is or if this could cause any potential damage to your Pro Mini but I do know for sure this is the solution I used to program my pro mini and it works every time.

user16673: Change baudrate to 
UPLOAD_RATE=57600 

in Makefile (or via the GUI). I have seen your error many times and this fixes it, albeit on the 5V/16MHz mini USB variant. If 57600 does not work, try other values. I use this rate on my USB serial - may be different on bare Rx/Tx pins. 
You have probably not messed up your bootloader, that is rarer than people think. I think your Arduino has some invalid code running, and it keeps resetting until it finds valid code - when I had that problem, I pressed reset just before punching enter for 'make upload'. Even if it does that, you've got perhaps 0.5s to initiate an upload after reset. 
Do correct me if I'm wrong.

user19394: 
Check connections, make sure RX-TX lines are crossing over.
Arduino -> Preferences -> Show verbose output during - check upload will give you better visibility what is happening.
When Arduino says "Uploading..." briefly press reset. The upload should start.

But one thing that helped me was... try different USB-UART adapter. For some reason the one which looked like (and was) cheap knockoff worked like a charm.
As a general advice, when sourcing parts from Chinese manufacturers I learned to be redundant - I usually order a bit more than I need and from mixed sources.

user16680: I had the same problem and I used a magnifying glass to check the processor.  I bought my clones off of eBay and they are using the ATMega168 (3.3V, 8 MHZ) processor.  Once I realized my mistake and switched to the correct processor version, the upload was seamless.  
I'm using an "FTDI FT232RL USB to TTL Serial Converter Adapter Module 5V and 3.3V For Arduino" for the programming connection, with

DTS-DTS;
Rx-Tx;
Tx-Rx;
VCC-VCC;
GND-GND, and;
GND-CTS.

I didn't even need to use the "reset" workaround of holding down the reset button before pressing the upload button and releasing when the words "Maximum is ..." appear in the output window.

user18658: rx -> tx
tx -> rx
Please check your connections.

7531: <p>I recently bought an Arduino Pro Mini(3.3V 328p, 8MHz) along with a CP2102 USB to TTL UART convertor. When I try to upload a sketch to the Pro Mini using it, I get a <code>avrdude:stk500_recv(): programmer is not responding</code> error. My connection was like </p>

<pre><code>Arduino pro mini                CP2102
TXO  ----------------------------&gt; TXD
RXI  ----------------------------&gt; RXD
VCC  ----------------------------&gt; 3V3
GND  ----------------------------&gt; GND
DTR  ----------------------------&gt; DTR
</code></pre>

<p>I tried inter-connecting the TXO and RXI pins and had no luck. Also pressing and releasing the reset button on the Pro Mini doesn't seem to work either.  I also tried programming it with my Arduino Uno, by removing the 328 and connecting correspondingly. Still no use. </p>

<p>Does any one have any ideas?</p>
 14843: <p>In the Arduino IDE for my Pro Mini I have to select the board: 
"Arduino Deumilanove or Diecimila"</p>

<p>I'm not sure why this is or if this could cause any potential damage to your Pro Mini but I do know for sure this is the solution I used to program my pro mini and it works every time.</p>
 16673: <p>Change baudrate to </p>

<pre><code>UPLOAD_RATE=57600 
</code></pre>

<p>in <code>Makefile</code> (or via the GUI). I have seen your error many times and this fixes it, albeit on the 5V/16MHz mini USB variant. If 57600 does not work, try other values. I use this rate on my USB serial - may be different on bare Rx/Tx pins. </p>

<p>You have probably not messed up your bootloader, that is rarer than people think. I think your Arduino has some invalid code running, and it keeps resetting until it finds valid code - when I had that problem, I pressed reset just before punching enter for 'make upload'. Even if it does that, you've got perhaps 0.5s to initiate an upload after reset. </p>

<p>Do correct me if I'm wrong.</p>
 19394: <ol>
<li>Check connections, make sure RX-TX lines are crossing over.</li>
<li><strong>Arduino</strong> -> <strong>Preferences</strong> -> <strong>Show verbose output during</strong> - check <strong>upload</strong> will give you better visibility what is happening.</li>
<li>When Arduino says "Uploading..." briefly press reset. The upload should start.</li>
</ol>

<p>But one thing that helped me was... try different USB-UART adapter. For some reason the one which looked like (and was) cheap knockoff worked like a charm.</p>

<p>As a general advice, when sourcing parts from Chinese manufacturers I learned to be redundant - I usually order a bit more than I need and from mixed sources.</p>
 16680: <p>I had the same problem and I used a magnifying glass to check the processor.  I bought my clones off of eBay and they are using the ATMega168 (3.3V, 8 MHZ) processor.  Once I realized my mistake and switched to the correct processor version, the upload was seamless.  </p>

<p>I'm using an "FTDI FT232RL USB to TTL Serial Converter Adapter Module 5V and 3.3V For Arduino" for the programming connection, with</p>

<ul>
<li>DTS-DTS;</li>
<li>Rx-Tx;</li>
<li>Tx-Rx;</li>
<li>VCC-VCC;</li>
<li>GND-GND, and;</li>
<li>GND-CTS.</li>
</ul>

<p>I didn't even need to use the "reset" workaround of holding down the reset button before pressing the upload button and releasing when the words "Maximum is ..." appear in the output window.</p>
 18658: <p>rx -> tx<br>
tx -> rx</p>

<p>Please check your connections.</p>
