The MAX13235E transceiver on the CP2102N-EK will not transmit the first bits of data if left idle for more than 30s.
The MAX13235E transceiver on TXD enters AutoShutdown Plus mode after 30s of inactivity on the data bus. Exiting the mode requires a transition edge. The transceiver takes ~40uS to return to normal operation. This will cause incorrect data on the RS-232 side of the transceiver.
To workaround this issue, place the MAX13235E in always-on mode by moving the 1KOhm resistor at R13 to R23.
Hello, i have some design issues with your product CP2102.
On the attached datasheet (CP2102-9) the pin 17 is shown with "NC" label. In the attached schematic (CP2102N-EB-SCH) instead, pin 17 is shown with GPIO2 / 485 label. What does it mean? Are there 2 different versions of the same product? what is the function of pin 17? Is it related to RS485 protocol?
Thank you for your question regarding the CP2102 pinout. To clarify, the CP2102 and the CP2102N are different parts:
You are correct that on the CP2102, pin 17 is "NC", whereas on the CP2102N-QFN28, pin 17 is GPIO.2 / RS485. On the CP2102N, this pin can be configured as a general GPIO pin or as a special function output to be used as an RS485 transceiver enable signal.
I hope this helps, and please let us know if you have any questions.