I try to use Serial1 in ATmega328PB to communicate with RS-485 IC. I am having a problem when I burn boot loader. I read this forum , but still do not understand how to resolve this issue. Could you please kindly suggest how to resolve this problem? I attach the configuration under Tools. Thank you A…

Please note that I tried many available boards. The closet working one is GitHub - watterott/ATmega328PB-Testing: Atmel/Microchip ATmega328PB support for Arduino IDE . Serial1 can be used; however, I cannot set other pins, such as PD2 to high logic for drive enable of this IC (sn75hvd3082e).

RS485 generally means you have to toggle a pin to send... The bootloader used by MiniCore doesn't have that feature... It was added to one fork of optiboot here - looks trivial to port to other versions. RS-485 mode added committed 11:54A…

I try to use Serial1 in ATmega328PB to communicate with RS-485 IC. ... Arduino: 1.8.10 (Mac OS X), Board: "ATmega328, Yes (UART0), 328PB, BOD 4.3V, LTO disabled, External 16 MHz" So are you still trying to run the bootloader/upload on Serial0 ? What are you using for a device programmer?

Thank you @DrAzzy for your response and insight. You're right. The RS-485 library will set the TX drive enable to high and low logic during transmit data so I do not expect MiniCore to provide the feature. Your commit is a good idea. It may be useful for me in future. Thank you @westfw for your res…

I found one of the posts mentioned that GitHub - watterott/ATmega328PB-Testing: Atmel/Microchip ATmega328PB support for Arduino IDE has an auto band rate, but minicore does not have it. I tried loading a couple of band rates , such as 500000, 115200, 38400, and 9600, via Atmel Studio and then set 328…

Thank you for your help @westfw . I can use Serial to communicate with RS-485 after using either Atmel mEDBG or Arduino as ISP (ATmega32U4). However, Serial1 still does not work. I attach all programmers in this post. Thank you Programming using AVRISP mkII, USBasp, USBtinyISP (MiniCore), USBasp (Mi…

I can use Serial to communicate with RS-485 after using either Atmel mEDBG or Arduino as ISP (ATmega32U4). However, Serial1 still does not work. I attach all programmers in this post. I'm pretty sure that "Can't get Serial1 to work with RS485" is an entirely different problem than "can't upload c…

Thank you @westfw . I will create a new thread based on your suggestion. The 485 IC is sn75hvd3082e. Thank you again for your help :slight_smile:

I found out that my code tries to use both SPI0 and UART1 at the same time (MOSI0 and TXD1 share the same pin, MISO0 and RXD1 share the same pin). This is no problem with MiniCore. We just need to fix band rate and choose the right programmer interface in order to work with ATmega328PB Xplained Mini…

Program ATmega328PB Xplained Mini using MiniCore

Development Tools Uploading

westfw March 17, 2020, 8:53am 7

It’s not using the right programmer type in the avrdude cmd line for an xplained mini.
See if there is an “medbg” entry is the list of programmers.

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Program ATmega328PB Xplained Mini using MiniCore

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