Accessing the Internet via the W5100

This program shows how to communicate with the W5100 chip from Wiznet. This chip can be accessed by any microcontroller with the ability to do SPI communication, and gives the controller the ability to act as a host on the Internet or any other network that uses Internet Protocol. The code in this program was written as an Arduino sketch, but can be altered to use on most microcontrollers that have a C compiler available.

The changes needed to migrate from Arduino will include:

• include the standard header file <stddint.h>, and change some of the types. Replace the Arduino type byte by uint8_t and replace the Arduino type word by uint16_t.
• Replace the SPI driver functions in this program with corresponding functions for SPI on your microcontroller. The functions to replace are wiz_select, wiz_unselect, wiz_read, wiz_write.
• Replace the code in the setup function that sets up the pins that connect to the W5100. The replacement code will do the necessary setup for SPI on your microcontroller.
• If you use a W5100 socket other than socket 0, the socket arguments in all the WISZ_…(0) symbols will have to be adjusted to match, and you will have to write appropriate definitions for SOCKx_RX_BASE, SOCKx_TX_BASE, SOCKx_RX_MASK, and SOCKx_TX_MASK. I've written suggested definitions at the end of this article.
• Every Arduino sketch contains a setup function and a loop function. The Arduino runtime treats these functions as though they were called from a C program like

  int main ()
  {
     setup();
     for (;;)
        loop();
  }
  

  You can take this into account if you adapt the wiztalk code.

Click to see the source file wiztalk.pde from the demo program.

W5100 Buffer Allocation

The W5100 contains two 8K-byte buffer blocks: one for received data, and one for transmitted data. You can allocate this space to the four sockets in 1K, 2K, 4K, or 8K blocks by setting the WIZ_RMSR register for receive-buffer allocations, and WIZ_TMSR for transmit buffer allocations. If you use the code example below, setting the …_RX_SIZE and …_TX_SIZE symbols to match your allocation, then the …_BASE and …_MASK definitions can be used unchanged to set up the values used by the wiztalk program.

// Define Receive and Transmit buffer sizes and addresses for the sockets we will use ..
#define SOCK0_RX_SIZE  2048
#define SOCK0_TX_SIZE  2048
#define SOCK1_RX_SIZE  2048
#define SOCK1_TX_SIZE  2048
#define SOCK2_RX_SIZE  2048
#define SOCK2_TX_SIZE  2048
#define SOCK3_RX_SIZE  2048
#define SOCK3_TX_SIZE  2048

#define SOCK0_RX_BASE  WIZ_RX_BUFFER_BASE
#define SOCK0_RX_MASK  (SOCK0_RX_SIZE - 1)
#define SOCK0_TX_BASE  WIZ_TX_BUFFER_BASE
#define SOCK0_TX_MASK  (SOCK0_TX_SIZE - 1)

#define SOCK1_RX_BASE  (SOCK0_RX_BASE+SOCK0_RX_SIZE)
#define SOCK1_RX_MASK  (SOCK1_RX_SIZE - 1)
#define SOCK1_TX_BASE  (SOCK0_TX_BASE+SOCK0_TX_SIZE)
#define SOCK1_TX_MASK  (SOCK1_TX_SIZE - 1)

#define SOCK2_RX_BASE  (SOCK1_RX_BASE+SOCK1_RX_SIZE)
#define SOCK2_RX_MASK  (SOCK2_RX_SIZE - 1)
#define SOCK2_TX_BASE  (SOCK1_TX_BASE+SOCK1_TX_SIZE)
#define SOCK2_TX_MASK  (SOCK2_TX_SIZE - 1)

#define SOCK3_RX_BASE  (SOCK2_RX_BASE+SOCK2_RX_SIZE)
#define SOCK3_RX_MASK  (SOCK3_RX_SIZE - 1)
#define SOCK3_TX_BASE  (SOCK2_TX_BASE+SOCK2_TX_SIZE)
#define SOCK3_TX_MASK  (SOCK3_TX_SIZE - 1)