MBED RPC with W5500 Ethernet Shield

Remote Procedure Call

>In computer science, a remote procedure call (RPC) is an inter-process communication that allows a computer program to cause a subroutine or procedure to execute in another address space (commonly on another computer on a shared network) without the programmer explicitly coding the details for this remote interaction.http://en.wikipedia.org/wiki/Remote_procedure_call

*source – http://uw714doc.sco.com/en/SDK_netapi/rpcpD.how_RPC_works.html

HW – FRDM-KL25Z + W5500 Ethernet Shield

• http://developer.mbed.org/platforms/KL25Z/

• http://developer.mbed.org/components/W5500-Ethernet-Kit-for-IoT/–HW connection : D10 – SCS / D11 – MOSI / D12 – MISO / D13 – SCLK

SW – mbed RPC

The server that executes remote procedure call (RPC) commands through HTTP. mbed RPC @developer.mbed.org/handbookIn RPC library, a simple HTTP Server can execute RPC commands sent from HTTP Client. This library uses EthernetInterface (lwIP) and mbedOS.

RPC command

The RPC command is encoded in this way :

• the container that wraps a skeleton’s ID

• the method that will be invoked

• parameters that will be inputted (optional)

• Command examplesPUT command : “/DigitalOut/new?arg=LED2&name=led2” GET command : “/led2/write?arg=1”

Request Handlers

To process requests, the server relies on RequestHandler. Each RequestHandler is assigned to a request type. Each type of request is assigned to a certain role :

• PUT requests to create new objects

• DELETE requests to delete objects

• GET requests to call a function of an object

Porting Ethernet Interface to W5500Interface

Here is a guide on how to modify :

• Folk HTTP-Server in you program workspace

• Delete 2 Folders; EthernetInterface(lwIP) & mbed-RTOS in HTTP-Server

• Added array for MAC Address which was written at Source Hardware Address Register in W5500. uint8_t mac_addr[6] = {0x00, 0x08, 0xDC, 0x00, 0x01, 0x02};`

• Change EthernetInterface() and set SPI Interface for W5500 /* Use EthernetInterface *EthernetInterface eth; *if(eth.init()) *int ret = eth.init("192.168.77.34", "255.255.255.0", "192.168.77.1"); */ /* ----- Use W5500 Ethernet Shied -----*/ SPI spi(D11, D12, D13); /* mosi, miso, sclk */ //spi.frequency(12500000); /* Optional : set proper SPI clock */ EthernetInterface eth(&spi, D10, D9); /* spi, cs, reset(dummy) */ ... /* ----- Use W5500 Ethernet Shied -----*/

• Set Network configuration: I will use fixed Address. /* in case of using W5500 Ethenret Shield */ int ret = eth.init(mac_addr, "192.168.77.34", "255.255.255.0", "192.168.77.1"); /* in case of using W550io (has a unique real MAC address) */ //int ret = eth.init("192.168.77.34", "255.255.255.0", "192.168.77.1");

Repository : Users » embeddist » Code » HTTP-Server_W5500Interface

http://developer.mbed.org/users/embeddist/code/HTTP-Server_W5500Interface/

Demo – Using a browser for HTTP Client

Here is a quick guide on how to run this program :

1 / 5

• Compiles this program and copies it to the mbed

• Open TeraTerm (install it if you don’t have it), select serial and choose the port named “mbed Serial Port”

• Reset your mbed

• The IP address should appear in teraterm. In this example, I will use 192.168.77.34

• Open your browser and go to http://192.168.77.34

• If everything is ok, you should see a webpage.

• Create Red LED as arg=LED1 and name=RLED

• To procedure, send the command: RLED/write 0

• To procedure, send a command: RLED/write 1