JAJSEA1 December 2017 PGA302
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 will not be 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 right after the read response command field is sent. Enough time exist between the command field and data field in order to allow the signal drivers time 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 will transmit 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 23.