How to use the

I²C EEPROM & Bcd Plugins 

Index

Overview

External EEPROM memory is often a necessary addition to embedded projects, however, troubleshooting at the hardware level can be frustrating and time consuming.  The I²C plugin can remove the doubt about the software being at fault.  The ability to run the simulation and see at a glance the data being written to the external EEPROM Makes debugging communications much more straightforward.  The I²C EEPROM plugin can simulate a device up to 64k bytes covering a broad range of applications.  

When numerical data needs to be quickly read 7-segment and 12-segment are usually a good choice.   

This tutorial will show how to:

• configure the plugins
• log and save I²C communications data 
• display output in BCD or hexadecimal

The Project

• Start SourceBoost IDE.
• Locate and open the i2c project.
• Build the project.

This part of the code in i2cmain.c contains the high level control:

.
.
.
for(num = 0;num < 255;num++)
{
/* Writes address number to the address Location */
ByteWrite( 0x50, 0, num, num+1 ); 

/* The following line used to display in BCD */ 
PORTB=char_to_bcd(RetrieveData( 0x50, 0, ( num - 1 ))); /* Reads back to port B in BCD*/
/* The following line used to display in hex */
/* PORTB=RetrieveData( 0x50, 0, ( num - 1 )); /* Reads back to port B in hexadecimal*/
}.
.
.

The for loop controls the addresses written to and increments the values sent as data.  The first output line converts the output to BCD form so the data will display correctly in that format.  The second  output line does not convert the output  so the data will display correctly in hexadecimal.

Once the project has been built enter debug mode by clicking the bug  on the tool bar. 

Configuring the Plugin

Configure your plugins like this:

To change to hex output check the radio button.

I²C Log Files

The output from the I2C log popup can be saved to file 

• To save a current log right click on the plugin window and select "save log to file".
• The file is stored in ASCII format .

A line by line explanation of the log listing above : 

• Pull-Up Data en Clock.
  Both the data and clock lines are pulled high signaling the bus is not busy.
  
  

• # Start signal received.
  When in the idle state and both the data and clock lines are pulled low by the master a start signal is sent.
  
  

• (ChipAddress = 1010000) (CodeAddress = 1010000) (R/W = 0)
  Send Acknowledge
  The EEPROMs address matches the code sent by the master so an acknowledge is sent by the EEPROM. 
  Since R/W = 0 a write is initiated.
  
  

• Address Byte = 00000000
  The first half of the  address to be written to is "00000000". (0x00)
  
  

• Send Acknowledge
  The first byte of the address was received. (The plugin is configured for two address bytes in this example)
  
  

• Address Byte = 0000000011110101
  This is the complete address: 11110101 (0xF5)
  
  

• Send Acknowledge
  The second address byte was received. 
  
  

• Data Byte = 11110101
  The data byte to be written is 11110101. (0xF5)
  
  

• Send Acknowledge
  The data byte was received.
  
  

• # Stop signal received.
  The data signal is pulled high by the master while it holds the clock signal high signaling a stop to the transmission.
  
  

• # Start signal received.
  Another start signal has been received from the master starting the next transmission.

Conclusion

The I²C EEPROM plugin offers a simple way to debug I²C communications software with out expensive hardware and hookup time.  This project has also shown the way the Bcd  plugin can be used to simplify the analysis of output data.

Return to Plugin Help

Legal Information

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