I2C Driver

The ASH WARE I2C eTPU Driver allows the Freescale eTPU to be connected to an I2C bus running in Standard-mode or Fast-mode, as either a master or slave node.  By using the output pin pad open drain capability, no external hardware is required for this connection.  This driver has been written to support both the eTPU and eTPU2 devices, and can run on any Freescale or STMicro chip with the eTPU/eTPU2 peripheral.

Versions

1.00 - initial production version

TBD - support multi-master (arbitration), support SMBus

I2C Master Features and Details

The I2C master driver supports the following features.

• up to 400 KHz operation, or better.  The actual limit depends upon the eTPU clock rate and other functions in the eTPU.
• read, write and combined format transfers
• 7-bit addressing
• START byte via combined format
• unexpected NACKs reported
• clock stretching (synchronization) by slave devices
• interrupt on transfer completion

Arbitration (multi-master), high-speed mode, CBUS and 10-bit addressing are not currently supported. The I2C master solution uses 4 consecutive eTPU channels and their associated pins. The first two must be connected to the SCL wire, the second two to the SDA wire. They function as follows:

base channel: SCL_out

base channel+1: SCL_in

base channel+2: SDA_out

base channel+3: SDA_in

I2C Slave Features and Details

The I2C slave driver supports the following features.

• up to 400 KHz operation, or better.  The actual limit depends upon the eTPU clock rate and other functions in the eTPU.
• programmable 7-bit address
• read, write and combined format transfers
• programmable acceptance of general calls
• handles START bytes
• interrupt on read request and transfer completion
• supports a wait-for-read-data mode wherein the slave driver holds the SCL wire low when a read request is received until the host has filled the read data buffer and alerted that eTPU that the data is ready.

The I2C slave solution uses 4 consecutive eTPU channels and their associated pins. The first two must be connected to the SCL wire, the second two to the SDA wire. They function as follows:

base channel: SCL_in

base channel+1: SCL_out

base channel+2: SDA_in

base channel+3: SDA_out

Example Waveforms

The following waveforms show the SCL and SDA wires during a write and read transfer.  Both a master and slave have been instantiated on a single eTPU, and connected together.  Signal levels for all the master channels (write transfer), and all the slave channels (read transfer) are shown as well.

Testing

Testing includes 100 % code and jump coverage of the eTPU software. All features described in the User Manual have been tested.

Guarantees

All requirements derived from the User Manual are guaranteed to be met. No other guarantees are made or implied. Specifically, determination of suitability for a particular application is the responsibility of the purchaser. If not fully satisfied, delete and return all materials within 60 days of purchase for a full refund.  Workmanship is guaranteed for one year.  Any software issues found and reported within one year will be fixed at no cost by ASH WARE.

Deliverables

• User Manual
• I2C eTPU C source code files etec_i2c_master.[c,h] and etec_i2c_slave.[c,h] that implement the I2C driver functionality in the eTPU.  These are configured for use with the ETEC eTPU C Compiler, but can be configured to work with other compilers if necessary (ETEC yields the best performance).
• All the eTPU build outputs, built with ETEC V2.00B.
• eTPU Simulator test suite that tests all I2C master and slave features with 100% code and jump coverage.
• Host-side I2C driver software that initializes and works with the eTPU.  This can be used as-is or modified for specific application requirements.
• Test / example host-side application software.
• eTPU System Simulator test suite for the I2C host software.

Consulting

With the purchase of the initial license comes 4 hours of consulting time. Additional hours are billed at an hourly rate of $180 USD.

Licensing

The baseline license is a per-product license.  Purchase of a license entitles the purchaser to use the eTPU drivers on a single product. If the driver were to be used on another product, an extension license would need to be purchased. ASH WARE receives no royalties.  Additional licensing options are available - contact ASH WARE for details as well as pricing for all license options.

A Licensing Agreement must be in place prior to delivery.

Royalties

Each license is royalty free. ASH WARE receives no per unit royalty.

Evaluation Kit

An evaluation kti is available upon request.  It consists of all deliverables except the eTPU source code, allowing users to test that the software will meet their needs.