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Note on Using the Serial Expansion Interface(SEI)

Product name
 
TOSHIBA Microcontrollers TLCS-870 Family  TLCS-870/C Series
  • TMP86C407/I/S
  • TMP86C807/I/S
  • TMP86F807
  • TMP86P807
  • TMP86C408/I/S
  • TMP86C808/I/S
  • TMP86F808
  • TMP86P808
  • JT5BR6
  • TMP86FH09
  • TMP86F809
  • TMP86F409
  • TMP86CH09
  • TMP86C809
  • TMP86CH87R
  • TMP86CM87R
  • TMP86PM87R

We would like to inform you of the following note on using the Serial Expansion Interface (SEI) incorporated in some of Toshiba’s TLCS-870/C Series 8-bit microcontrollers. If you need any further information, please contact your local Toshiba sales representative.

Note on using the SEI

  The MISO pin of a slave device is set as an output when the SEE bit in the SECR register is set to 1 (enable SEI operation) regardless of the /SS pin state.
  The MISO pin is not put in a high-impedance state even if the /SS pin of the slave device is driven high. To place the MISO pin in a high-impedance state, the SEE bit must be cleared to 0 (disable SEI operation).
  In a system in which the MISO pins of more than one slave device are interconnected, the SEE bit of each inactive slave device must be cleared to 0 to prevent the MISO bus from being occupied by inactive slave devices. The measures to be taken are explained below.

Measures to be taken in a system comprising multiple slave devices
  • Slave device
       ・ Each slave device should set the SEE bit to 1 only when the /SS pin is low.
       · As soon as the /SS pin is driven high, each slave device must clear the SEE bit to 0 to release the MISO pin.
  • Master device
       After the master device drives the /SS pin of the selected slave device low, a wait period must be inserted by software to allow the slave device to set up for communications with the master device.
     The master device should start transferring data to the slave device by giving careful consideration to the setup time of the slave device.
      If the master device wants to communicate with another slave device after completing an SEI transfer, a wait period must be inserted by software to allow the current active slave device to release the MISO bus. Careful consideration should be given to transfer intervals.
Processing example for a system comprising one master and multiple slaves
(SECR<CPHA>=1, <CPOL>=1, active slave = slave 1)

Processing example for a system comprising one master and multiple=

  • *1,  The master device should insert a wait period by software. The master device should start transferring data by giving careful consideration to the setup time of the slave device.
  • *2,  When the device is configured as a slave with SECR<CPHA>=0, transfer data must be set in the SEDR register while the /SS pin is high. We recommend setting SECR<CPHA>=1, in which case transfer data can be written regardless of the /SS pin state.
  • *3,  If the master wants to communicate with another slave device, a wait period is required to allow the current active slave device to release the bus. Careful consideration should be given to transfer intervals.

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·Before creating and producing designs and using, customers must also refer to and comply with the latest versions of all relevant TOSHIBA information and the instructions for the application that Product will be used with or for.