Epson S1C31D50 Technical Manual

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15 Quad Synchronous Serial Interface (QSPI)15-14 Seiko Epson Corporation S1C31D50/D51 TECHNICAL MANUAL(Rev. 2.00)Table 15.5.4.1 DMA Data Structure Configuration Example (for 16-bit Data Transmission)Item Setting exampleEnd pointer Transfer source Memory address in which the last transmit data is storedTransfer destination QSPI_nTXD register addressControl data dst_inc 0x3 (no increment)dst_size 0x1 (haflword)src_inc 0x1 (+2)src_size 0x1 (halfword)R_power 0x0 (arbitrated for every transfer)n_minus_1 Number of transfer datacycle_ctrl 0x1 (basic transfer)15.5.5 Data Reception in Register Access Master ModeA data receiving procedure and operations in register access master mode are shown below. Figures 15.5.5.1 and15.5.5.2 show a timing chart and flowcharts, respectively.Data receiving procedure1. Set the QSPI_nCTL.DIR bit to 1 when QSPI Ch.n is set to dual or quad transfer mode. (This setting is notnecessary in single transfer mode.)2. Assert the slave select signal for the external slave device to be accessed by controlling the QSPI_nCTL.MSTSSO bit or the general-purpose output port used for an extra slave select signal output (if necessary).3. Check to see if the QSPI_nINTF.TBEIF bit is set to 1 (transmit buffer empty).4. Write dummy data (or transmit data) to the QSPI_nTXD register.5. Wait for a transmit buffer empty interrupt (QSPI_nINTF.TBEIF bit = 1).6. Write dummy data (or transmit data) to the QSPI_nTXD register.7. Wait for a receive buffer full interrupt (QSPI_nINTF.RBFIF bit = 1).8. Read the received data from the QSPI_nRXD register.9. Repeat Steps 6 to 8 until the end of data reception.10. Negate the slave select signal that has been asserted in Step 2 by controlling the QSPI_nCTL.MSTSSO bitor the general-purpose output port (if necessary).Note: To perform continuous data reception without stopping QSPICLKn, Steps 8 and 6 operationsmust be completed within the QSPICLKn cycles equivalent to “Data bit length - 1” after Step 7.Data receiving operationsIn single transfer mode (QSPI_nMOD.TMOD[1:0] bits = 0), QSPI Ch.n operates similar to legacy SPI devices.The data receiving operation starts simultaneously with a data sending operation when transmit data (may bedummy data if data transmission is not required) is written to the QSPI_nTXD register. Transmit data are out-put from the QSDIOn0 pin and receive data are input from the QSDIOn1 pin.In dual or quad transfer mode (QSPI_nMOD.TMOD[1:0] bits = 1 or 2), transmit data are not sent at data recep-tion. Writing dummy data to the QSPI_nTXD register triggers the QSPI Ch.n to start supplying the data transferclock from the QSPICLKn pin to the slave device.The QSPICLKn pin outputs the number of clocks specified by the QSPI_nMOD.CHLN[3:0] bits. The re-ceive data bits input from the QSDIOn pins, according to the transfer mode specified by the QSPI_nMOD.TMOD[1:0] bits, are shifted into the shift register in sync with these clocks.When the last clock is output from the QSPICLKn pin and receive data bits are all shifted into the shift register,the received data is transferred to the receive data buffer and the QSPI_nINTF.RBFIF bit is set to 1. At the sametime QSPI Ch.n issues a receive buffer full interrupt request if the QSPI_nINTE.RBFIE bit = 1. After that, thereceived data in the receive data buffer can be read through the QSPI_nRXD register.Note: If data of the number of the bits specified by the QSPI_nMOD.CHLN[3:0] bits and QSPI_nMOD.TMOD[1:0] bits is received when the QSPI_nINTF.RBFIF bit is set to 1, the QSPI_nRXD register isoverwritten with the newly received data and the previously received data is lost. In this case, theQSPI_nINTF.OEIF bit is set.