SLDS216B December 2017 – February 2025 PGA302
PRODUCTION DATA
The read operation requires two consecutive transmission frames to move data from the target to the controller. The first frame is the Read Initialization Frame. It tells the target to retrieve data from a particular location within the target 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 controller commands it to be sent in the subsequent frame called the Read Response Frame. During the read response frame the data direction changes from controller → target to target → controller 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 target device. After this wait time is complete the target will transmit the requested data. The controller device is expected to have switched its signal drivers and is ready to receive data. The Read frames are shown in Figure 6-15.