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PSoC™ 4 Forum Discussions

keno_4227451
Level 1
Level 1
First like given

Hello.

I want to communicate to other device by using PSoC I2C component but I dont know how to use.

I want to put PSoC as master and the device as slave and just want to write.

Could anyone give me some easy sample code to use I2C??

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1 Solution
Bob_Marlowe
Level 10
Level 10
First like given 50 questions asked 10 questions asked

Byte I2C interface is quite simple: After setting up the component and starting it you use

    I2C_MasterSendStart(DeviceAddress,I2C_WRITE_XFER_MODE);    // Initialize a transaction for writing

    I2C_MasterWriteByte(Register);                // Indicate which register you want to write to

    I2C_MasterWriteByte(Value);                // Write to register

    I2C_MasterSendStop();                    // End of transaction

When you want to read from a device you use (example for reading two bytes

    I2C_MasterSendStart(DeviceAddress,I2C_WRITE_XFER_MODE);    // Initialize a transaction for writing

    I2C_MasterWrite(Register);                // Indicate which register you want to write to

    I2C_MasterSendRestart(DeviceAddress,I2C_READ_XFER_MODE);

    I2C_MasterReadByte(I2C_ACK_DATA);            // Read from register

    I2C_MasterReadByte(I2C_NAK_DATA);            // Read from register, last byte is NAKed

    I2C_MasterSendStop();                    // End of transaction

Not too difficult. Keep in mind that most of the APIs (except those for reading a byte) return a status byte which, when non-zero indicate an error condition.

The high-level APIs must be used in this way:

Writing to slave Count bytes

I2C_MasterWriteBuf(SlaveAddress,DataPtr,Count,I2C_MODE_COMPLETE_XFER);

Reading from Slave sending register/command byte first:

I2C_MasterWriteBuf(SlaveAddress,&RegAddress,1,I2C_MODE_NO_STOP);

I2C_MasterReadBuf(SlaveAddress,DataPtr,Count,I2C_MODE_REPEAT_START);

*** Important: I2C needs two pull-up resistors (~ 2.2K) on SDA and SCL. The pins should be configured as "Open drain, drives low" and the initial drive level = High.

Bob

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6 Replies
Bob_Marlowe
Level 10
Level 10
First like given 50 questions asked 10 questions asked

Byte I2C interface is quite simple: After setting up the component and starting it you use

    I2C_MasterSendStart(DeviceAddress,I2C_WRITE_XFER_MODE);    // Initialize a transaction for writing

    I2C_MasterWriteByte(Register);                // Indicate which register you want to write to

    I2C_MasterWriteByte(Value);                // Write to register

    I2C_MasterSendStop();                    // End of transaction

When you want to read from a device you use (example for reading two bytes

    I2C_MasterSendStart(DeviceAddress,I2C_WRITE_XFER_MODE);    // Initialize a transaction for writing

    I2C_MasterWrite(Register);                // Indicate which register you want to write to

    I2C_MasterSendRestart(DeviceAddress,I2C_READ_XFER_MODE);

    I2C_MasterReadByte(I2C_ACK_DATA);            // Read from register

    I2C_MasterReadByte(I2C_NAK_DATA);            // Read from register, last byte is NAKed

    I2C_MasterSendStop();                    // End of transaction

Not too difficult. Keep in mind that most of the APIs (except those for reading a byte) return a status byte which, when non-zero indicate an error condition.

The high-level APIs must be used in this way:

Writing to slave Count bytes

I2C_MasterWriteBuf(SlaveAddress,DataPtr,Count,I2C_MODE_COMPLETE_XFER);

Reading from Slave sending register/command byte first:

I2C_MasterWriteBuf(SlaveAddress,&RegAddress,1,I2C_MODE_NO_STOP);

I2C_MasterReadBuf(SlaveAddress,DataPtr,Count,I2C_MODE_REPEAT_START);

*** Important: I2C needs two pull-up resistors (~ 2.2K) on SDA and SCL. The pins should be configured as "Open drain, drives low" and the initial drive level = High.

Bob

Sorry, I have a question.

When I put

    I2C_MasterSendStart(DeviceAddress,I2C_WRITE_XFER_MODE);    // Initialize a transaction for writing

    I2C_MasterWriteByte(Register);                // Indicate which register you want to write to

    I2C_MasterWriteByte(Value);                // Write to register

    I2C_MasterSendStop();                    // End of transaction

and build it, error comes up and that says they are undefined reference.

Is there any other thing I should do??

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Can you please post your complete project or a shortened version that shows the error so that we all can have a look at all of your settings. To do so, use

Creator->File->Create Workspace Bundle (minimal)

and attach the resulting file.

Bob

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keno_4227451
Level 1
Level 1
First like given

Thank you so much!!!

I will try it!!

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keno_4227451
Level 1
Level 1
First like given

Sorry I dont know how to attach it...

I attach the image instead.

図2.png図3.png

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For your device the API names are formed as I2C_1_I2CMasterSendStart(). Look into the component's datasheet (right click)

To attach a file here, click on "advanced Editor"

Bob

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