USB power help please
T Chap
Posts: 4,223
I am putting a VNV1L on a PCB, this is the first application where I am using any USB chips.
A tech at FTDI told me to put a header on the PCB to program the VNC1L with using the USB>TTL232 cable they sell. [noparse][[/noparse]TTL-232R cable]
So I started putting in the header and it struck me that I have an error in that on the USB plug I have put VCC [noparse][[/noparse]5v] from the boards supply. This means that whatever I plug into the the USB port will see 5 volts from the board. Please correct me if wrong, but isn't the intended use of the VCC on that USB port for times when there is no power on the PCB, or you want to power the USB chip from an external source? In my case, after the programming is done via the TTL cable, the USB port will hold a thumbdrive, and the VNC1L will get power from the board.
Shouldn't I get rid of the power to the USB plug as it is not needed?
Next issue, since the TX, RX, CTS, and RTS are multed to a Propeller from the header and VNV1L, is there any reason to possibly put a 200 ohm in series to the Prop?
Thanks for any pointers.
A tech at FTDI told me to put a header on the PCB to program the VNC1L with using the USB>TTL232 cable they sell. [noparse][[/noparse]TTL-232R cable]
So I started putting in the header and it struck me that I have an error in that on the USB plug I have put VCC [noparse][[/noparse]5v] from the boards supply. This means that whatever I plug into the the USB port will see 5 volts from the board. Please correct me if wrong, but isn't the intended use of the VCC on that USB port for times when there is no power on the PCB, or you want to power the USB chip from an external source? In my case, after the programming is done via the TTL cable, the USB port will hold a thumbdrive, and the VNC1L will get power from the board.
Shouldn't I get rid of the power to the USB plug as it is not needed?
Next issue, since the TX, RX, CTS, and RTS are multed to a Propeller from the header and VNV1L, is there any reason to possibly put a 200 ohm in series to the Prop?
Thanks for any pointers.
547 x 772 - 94K