IoT Gateway Ethernet-RS485 based on STM32

This post is dedicated to DIY development of the Ethernet-RS485 gateway. The purpose of this gateway is to provide centralized control of Mysensors' nods by the smart home controller.
ORIGINAL POST
By Владимир dab0g
details

2021-05-31-2.jpg 0.Connect-your-Arduino-to-the-Internet-as-a-Web-Server 1.Connect your Arduino to the Internet as a Web Server 0.Connect your Arduino to the Internet as a Web Server

This gateway is built on the basis of MK STM32F103CB (8)T6. As an Ethernet chip is a fairly well-known chip from WIZnet – W5500. The transport of this gateway in the Mysensors network is the wired interface of RS485. The RS485 was chosen as the max13488EESA’T,in part because of its automatic mode of choice of the direction of admission/transmission.

 

So let’s go through the main parts of the gateway in more detail.

 

The heart of the gateway is the MK STM32F103CBT6 in the 48L’FN case. MK is built on the Core Cortex-M3, has 128KB built-in flash memory and 20KB RAM. The MK’s regular frequency is 72MHz, but if you do not use the built-in USB port, the frequency can be accelerated to 128MHz, it is quite stable. MK is powered by 3.3B. Two quartz, 8MHz and 32.768KHz are needed for full operation. There is an SWD interface for programming and debugging. MK can be replaced with STM32F103C8T6, it is currently quite passable from memory.

 

Ethernet chip W5500. Inside has a Cortex M0 core, for communication with the outside world there is a port SPI (speed up to 80 MHz). At 100Mbps, Full Link has a consumption of 132mA. There is support for Wake on LAN, to indicate its mode is able to manage 4 LEDs 4 (SPD / DUP / ACT / Link). With 32 kbytes of RAM buffer memory to ensure the TCP/IP package transfer process, the hardware provides up to 8 independent TCP/UDP sockets (channel connections). The hardware supports the following switching protocols of wired TCP/IP stack processing: TCP, UDP, MAC, ICMP, IPv4, ARP, IGMP, PPPoE. The range of working temperatures is -40…85 degrees C. Power voltage is 3.3B.

2021-05-31-2.jpg 0.Connect-your-Arduino-to-the-Internet-as-a-Web-Server 1.Connect your Arduino to the Internet as a Web Server 0.Connect your Arduino to the Internet as a Web Server

This gateway is built on the basis of MK STM32F103CB (8)T6. As an Ethernet chip is a fairly well-known chip from WIZnet – W5500. The transport of this gateway in the Mysensors network is the wired interface of RS485. The RS485 was chosen as the max13488EESA’T,in part because of its automatic mode of choice of the direction of admission/transmission.

 

So let’s go through the main parts of the gateway in more detail.

 

The heart of the gateway is the MK STM32F103CBT6 in the 48L’FN case. MK is built on the Core Cortex-M3, has 128KB built-in flash memory and 20KB RAM. The MK’s regular frequency is 72MHz, but if you do not use the built-in USB port, the frequency can be accelerated to 128MHz, it is quite stable. MK is powered by 3.3B. Two quartz, 8MHz and 32.768KHz are needed for full operation. There is an SWD interface for programming and debugging. MK can be replaced with STM32F103C8T6, it is currently quite passable from memory.

 

Ethernet chip W5500. Inside has a Cortex M0 core, for communication with the outside world there is a port SPI (speed up to 80 MHz). At 100Mbps, Full Link has a consumption of 132mA. There is support for Wake on LAN, to indicate its mode is able to manage 4 LEDs 4 (SPD / DUP / ACT / Link). With 32 kbytes of RAM buffer memory to ensure the TCP/IP package transfer process, the hardware provides up to 8 independent TCP/UDP sockets (channel connections). The hardware supports the following switching protocols of wired TCP/IP stack processing: TCP, UDP, MAC, ICMP, IPv4, ARP, IGMP, PPPoE. The range of working temperatures is -40…85 degrees C. Power voltage is 3.3B.

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