I’ve made my own PCB (Atmega328p + 16Mhz + FTDI FT231xs + NeoPixels). I’m having trouble uploading code via USB. I can use another Arduino as programmer to upload code. I’ve used this to verify the serial portion by echoing whatever I send it. I can send and receive serial data. So in my mind HW is working.
However, when I try to upload code using the USB-to-FTDI, I get stk500_recv(): programmer is not responding error and stk500_getsync(): not in sync. I’m looking at it using an O’scope and the TX line drops to about 2.5V. This doesn’t seem right.
Attached is my my board config (boards.txt)
myBoard.name=Led Ring Board myBoard.build.mcu=atmega328p myBoard.build.f_cpu=16000000L myBoard.build.core=arduino myBoard.build.variant=standard myBoard.build.board=AVR_PRO myBoard.bootloader.tool=avrdude myBoard.bootloader.low_fuses=0xFF myBoard.bootloader.high_fuses=0xDA myBoard.bootloader.extended_fuses=0x05 myBoard.bootloader.file=optiboot/optiboot_atmega328.hex myBoard.bootloader.unlock_bits=0x3F myBoard.bootloader.lock_bits=0x0F myBoard.upload.tool=avrdude myBoard.upload.protocol=arduino myBoard.upload.speed=19200 myBoard.upload.maximum_size=30720 myBoard.upload.maximum_data_size=2048
Also my PCB schematics. I apologize, I don’t have a PDF with the schematics.