Programmer for AVR on FT232R, help me deal with strange behavior

Question

Do it yourself

I had a homemade programmer on a sabzhe chip. Worked great and had no problems with it. Exactly until the moment he showed this miracle device to a friend. After that, he said goodbye to him safely.
It doesn't matter, I thought, and popping on the way home to the radio parts store, I bought myself a couple of FT232RLs in the hope of making myself two new ones, in reserve, and USB-> TTL is not superfluous in the household.
The layout of the board was messed up, so I quickly assembled the seals with LUT and assembled these adapters.
Here they are: And larger 1st: and 2nd: Collected, connected and then the fun began. Both devices behave absolutely identically, so I will describe the dances for only one.




When connected to USB, Windows is ahead of the COM port and USB Serial Converter. Both devices "Work fine" according to Windows. The native MProg program from the chip manufacturer happily detects it, reads the firmware parameters (EEPROM), allows you to change them and successfully saves it back to the chip. It would seem that everything is fine, the device works. I open the terminal (PuTTY) and set it on a new COM port, while there is no port error. I close TX and RX for the test and send a string through the terminal. The TXLED and RXLED lights on the board are blinking, but NOT A SINGLE character is returned back. The same situation when trying to flash AVRku (I tested on the 8th mega). The pipe finds the programmer, starts sewing, while the TXLED light blinks and falls out with an error, they say check the connection. I rang the tester right on the legs of FT and mega, everything is connected correctly. Food goes to her
It got to the point that I connected the TX and RX legs of both boards in pairs, connected them together, opened 2 terminals and tried to send data from one to the other. As you might guess, unsuccessfully. The transmit and receive lights are flashing but nothing more.

Who has any ideas about what's going on? I've already cracked my head on this problem. I rang all the contacts of all legs - there are no short circuits, the contacts are good everywhere.

Answer 1

Try to pull up all the used pins (rx, tx, ri, etc.) with external resistors. FTDI has 250 kOhm pull-ups, but I came across the fact that both zero and one are read from the “hanging” pin. Maybe it has to do with poor nutrition.