To date I have only powered my Nano via USB connected to a PC. Now I want to connect an HC05.
AFAIK the Nano shouldn't be connected to a PC via USB if its Rx/Tx pins are connected.
Am I right to assume it shoudl be ok to connect the Nano via USB to a battery pack and use the Rx/Tx pins?
Yes.
1 Like
Thanks.
Remember, when the (5v) battery pack is plugged int to the USB connector, Nano startup software will do its normal bootloader startup stuff on the TX pin.
I'm afraid you lost me at normal bootloader startup stuff on the TX pin.
When the board is first powered on, the bootloader software announces itself (for a short period of time) on the TX pin . . .
This might not be what you want.
You can avoid this if you program the board using ISP.
Thanks Larry.
If there's only data at the Tx pin at power-up, presumably as the HC05 won't be paired with anything else, it shouldn't be a problem?
Was just pointing out the phenomenon.
Note:
If the pin was connected to a relay circuit, undesirable results could occur.
Gotcha.
Many thanks.
the bootloader doesn't actually transmit anything, but it does enable the UART, which will behave like "pinMode(1, OUTPUT); digitalWrite(1, HIGH);" Like LarryD said; if it's connected to a relay or something similar, that could be a problem. If it's connected to some other serial port, it should be OK.
(the RX pin may also act like it's being "pulled up" by the USB/Serial Chip's output.)
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