SLDS231 August 2018 PGA305
PRODUCTION DATA.
The read operation requires two consecutive transmission frames to move data from the slave to the master. The first frame is the read-initialization frame. It tells the slave to retrieve data from a particular location within the slave device and prepare to send it over the OWI. The data location may be specified in the command field or may require additional data fields for complete data-location specification. The data is not sent until the master commands it to be sent in the subsequent frame called the read-response frame. During the read-response frame, the data direction changes from master → slave to slave → master immediately after the read response command field is sent. Enough time elapses between the command field and data field to allow the signal drivers to change direction. This wait time is 20 µs, and the timer for this wait time is located on the slave device. After this wait time is complete, the slave transmits the requested data. The master device is expected to have switched its signal drivers and is ready to receive data. The read frames are shown in Figure 15.