A digital interface unit for controlling data transfers between a first logic device and a second logic device wherein the first logic device transmits and receives data in a serial format and the second logic device transmits and receives data in a parallel format, said digital interface unit comprising:
- control means for receiving a first request to send command from said first logic device, said first request to send command initiating a first data transfer from said first logic device to said second logic device;
- said control means, responsive to said first request to send command, generating a first request to send control signal, said control means providing said first request to send control signal to said second logic device and then receiving a first clear to send control signal from said second logic device;
- said control means, responsive to said first clear to send control signal, generating a first clear to send command, said control means providing said first clear to send command to said first logic device and then receiving a first start of message command from said first logic device;
- said control means, responsive to said first start of message command, generating a reset signal;
- storage means for receiving said reset signal, said reset signal clearing said storage means;
- receiver means for receiving a first plurality of serial data bytes from said first logic device, for converting said first plurality of serial data bytes to a first plurality of parallel data bytes and for providing a data strobe signal;
- said storage means receiving said first plurality of parallel data bytes from said receiver means after said reset signal clears said storage means, said storage means, responsive to said data strobe signal, storing said first plurality of parallel data bytes;
- said control means receiving a first end of message command from said first logic device after said first logic device transmits a last serial data byte of said first plurality of serial data bytes to said digital interface unit;
- said control means, responsive to said first end of message command, generating a done command, said control means providing said done command to said first logic device, said done command when provided to said first logic device acknowledging transmission of said first plurality of serial data bytes from said first logic device to said digital interface unit;
- said control means, receiving a first data out request control signal from said second logic device;
- said control means, responsive to said first end of message command, said first clear to send control signal and said first data out request control signal, generating a read signal;
- said control means providing said read signal to said storage means, said read signal effecting a retrieving of said first plurality of parallel data from said storage means and a transmitting of said first plurality of parallel data from said storage means to said second logic device;
- said control means, responsive to said first end of message command, said first clear to send control signal and said first data out request control signal, generating a data in request control signal and a write data in control signal, said control means providing said data in request control signal and said write data in control signal to said second logic device, said data in request control signal and said write data in control signal effecting a writing of said first plurality of parallel data bytes in said second logic device;
- said storage means providing a data empty signal after a last parallel data byte of said first plurality of parallel data bytes is read from said storage means,
- said control means receiving said data empty signal from storage means, said control means, responsive to said data empty signal and said end of message command, generating an end of message control signal and providing said end of message control signal to said second logic device, said end of message control signal completing said first data transfer from said first logic device to said second logic device;
- said control means receiving a second request to send control signal from said second logic device, said second request to send control signal initiating a second data transfer from said second logic device to said first logic device;
- said control means, responsive to a second request to send control signal from said second logic device, generating a second request to send command;
- said control means providing said second request to send command to said first logic device and then receiving a second clear to send command from said first logic device;
- said control means, responsive to said second clear to send command, generating a second clear to send control signal, said control means providing said second clear to send control signal to said second logic device and then receiving a write data out control signal from said second logic device;
- said control means, responsive to said write data out control signal, generating a second start of message command, said control means providing said second start of message command to said first logic device;
- transmitter means for receiving a second plurality of parallel data bytes from said second logic device;
- said control means, responsive to said write data out control signal, generating a transmitter strobe signal, said control means providing said transmitter strobe signal to said transmitter means;
- said transmitter means, responsive to said transmitter strobe signal, latching said second plurality of parallel data bytes in said transmitter means, said transmitter means converting said second plurality of parallel data bytes to a second plurality of serial data;
- said control means transmitting said second plurality of serial data bytes to said first logic device after said control means provides said second start of message command to said first logic device;
- said control means, responsive to said write data control signal, generating an acknowledge control signal, said control means providing said acknowledge control signal to said second logic device, said acknowledge control signal indicating to said second logic device that said digital interface unit received each of said second plurality of parallel data bytes from said second logic device;
- said control means generating a second end of message command after a last serial data byte of said plurality of serial data bytes is transmitted from said digital interface unit to said first logic device;
- said control means providing said second end of message command to said first logic device, said second end of message command completing said second data transfer from said second logic device to said first logic device.