4 Uarts and 2 Ethernet possiblities
#1
We have below requirements and questions, please help with pointers for our research.

1. We need 4 UARTs
2. 2 ethernet(s) [100 Mbps is fine], one natively available, what is the best option to add second one?
3. WIFI/BLE

Though we look for Industrial Temperature, considering RockPro64 LTS' 0-70 temp is good for factories that we aim for.

How many hardware UARTs RockPro64 supports, somehow we could not find the straight answers. 
Is it possible to enable some GPIO pins to be UART? We want to connect 4 RS 485 channels on 4 UARTS, can RockPro64 could supply power for same along with 2 Ethernets while in use?
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#2
(04-04-2019, 12:20 PM)gops Wrote: 1. We need 4 UARTs

Is it possible to enable some GPIO pins to be UART? We want to connect 4 RS 485 channels on 4 UARTS

On the GPIO header, there is only the UART2DBG.
What I suggest you is to build a piggy back board with 2 SC16IS752, which is a Dual Uart chip attached on SPI bus, that way, you will get 4 GPIO with HalfDuplex capability for RS485.
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#3
Thank you, Is one UART design followed due to Raspberry PI compatible pins? 
As many RPI2 styled interfaces provides 1 or 2 UARTs.
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#4
(04-04-2019, 08:17 PM)gops Wrote: Thank you, Is one UART design followed due to Raspberry PI compatible pins? 
As many RPI2 styled interfaces provides 1 or 2 UARTs.

Non necessarily ... There is a second UART, the UART4 available on pins 19/21, but it is shared with SPI pins.
It is better to use those SPI pins for attaching the SC16IS752 chips ...
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#5
(04-04-2019, 12:20 PM)gops Wrote: 2. 2 ethernet(s) [100 Mbps is fine], one natively available, what is the best option to add second one?

Concerning a second NIC, I use a USB 3 Gigabit Ethernet adapter, it works quite well. To configure it, one needs to add a yaml file in /etc/netplan (in ubuntu)
LMM.
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#6
(04-05-2019, 09:58 AM)LMM Wrote:
(04-04-2019, 12:20 PM)gops Wrote: 2. 2 ethernet(s) [100 Mbps is fine], one natively available, what is the best option to add second one?

Concerning a second NIC, I use a USB 3 Gigabit Ethernet adapter, it works quite well. To configure it, one needs to add a yaml file in /etc/netplan (in ubuntu)
LMM.

Thanks for great suggestion martinayotte and LMM. 

Any recommendation as module for USB to Ethernet, instead of we connect USB to Ethernet from outside connector, I mean, we would like make a daughter board with a small PCB with host 4 RS 485 (with SC16IS752 x 2), 1 Ethernet USB port. Any concerns like how  RockPro64 help with power supply all ports.
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#7
i need a 1 rs485 uart on Rock64 board. does it possible to use UART2 with max485 level converter? Or i have to use 
SC16IS752 chip. Does it suported in kernel? My java application use /dev/tty style 485 usart for modbus communication.
May be exist better solution for my problem.
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#8
Beware that you also need to control RTS for RS485 flow direction ...
If you don't want to bother with driver or this flow direction, you are better luck using a USB-RS485 dongle such as this one :
https://www.ebay.ca/itm/2PCS-CH340-USB-t...1911412433
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#9
(06-27-2019, 09:29 AM)martinayotte Wrote: Beware that you also need to control RTS for RS485 flow direction ...
If you don't want to bother with driver or this flow direction, you are better luck using a USB-RS485 dongle such as this one :
https://www.ebay.ca/itm/2PCS-CH340-USB-t...1911412433

thank you for reply. I know about this pin for direction. In other forum (armbian) i saw yours post about using RTS signal for this. I have a allwiner board to but i can't find kernel module which support uart rts signal. I know about usb-485 adapters whis is cheap but i do not have free usb ports..
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#10
(06-27-2019, 11:23 AM)pistoletov Wrote:
(06-27-2019, 09:29 AM)martinayotte Wrote: Beware that you also need to control RTS for RS485 flow direction ...
If you don't want to bother with driver or this flow direction, you are better luck using a USB-RS485 dongle such as this one :
https://www.ebay.ca/itm/2PCS-CH340-USB-t...1911412433

thank you for reply.  I know about this pin for direction. In other forum (armbian) i saw yours post about using RTS signal for this. I have a allwiner board to but i can't find kernel module which support  uart  rts signal.  I know about usb-485 adapters whis is cheap but i do not have free usb ports..
RS485 might be difficult to control via software, if the speeds are high.

Actually, you might consider a Beaglebone Black or Green.  It has 5 UARTs available, and it can support RS485 with buffers (like the MAX485).  You can plug in a second Ethernet via USB.
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