www.forenex.com.tw
- 26 -
A-2. Read data form SPI Slave device.
(1) When Host wants to read back
N
data bytes from SPI Slave device. It should
add same number
N
of dummy bytes to be the last bytes of packet.
(2) When E2S received any packet form Ethernet. The E2S will assert a
completed SPI transition cycle that base on the protocol of SPI Slave Device.
And bypass entire packet to SPI Slave device without change.
(3) The return data packet includes invalid and valid data. The valid data will be
located as same as the dummy bytes which have been defined in packet.
E.g. If you want to read 4 Bytes data form AMIC A25LQ64,
The packet form Host should be “1 Byte C 3 Bytes A 4 Bytes Dummy”
When single packet processing is completed, the E2S will be returned 8 Bytes data to Host.
The valid data was after 4 position 4 bytes in E2S returned.
