Quatech 802.11B/G Especificaciones descargar pdf (Pagina 44)

5 – Serial Peripheral Interface

Page 38 Airborne Wireless LAN Node Module Data Book 100-8004-102G

Quatech, Inc. Confidential

5.4.4 SPI Read Data

The SPI Master may read data when available by sending the Read Data command.

Read Data Command

Table 16. SPI Read Data Command

Response

Length (2 Octets) – This tells the Master the number of octets that are waiting to be transmitted

to the Master.

Data (N Octets, N being the Length) – The data will be sent to the Master immediately after the

Length is sent.

Figure 14. Read Data Timing Diagram

Note:

• Data is transferred as long as /SS is asserted. Flow control for

transmissions from the Slave to the Master may be implemented by

having the Master assert and de-assert the /SS line. If /SS is de-

asserted, the transmission from the Slave will be halted, and the next

RDATA command will cause the Slave to continue transmitting data

starting at the byte after the byte on which the previous transmission

was halted

Command Length Value (0x00)

RDATA 1 Octet Bit 7 = 0

Bit 6 = 0

Bits 5:0 = 0 (reserved, must set to 0)

1 2 ... 39 40 41 42 43 44 45 46 47 48 49 ... 66 67

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Quatech 802.11B/G Especificaciones Pagina 44