Cypress Semiconductor CY8C21534 Spécifications télécharger pdf (Page 27)

The system has been designed to have several sections of the unit function in a

specific order. Every time the electronic class schedule is used, the unit follows the

same function flow which is shown in figure 14.

Figure 14: System Sequence Block Diagram.

As can be seen in the figure, when a user touches a button, the Control MCU sends a

logic 1 on the signal line that signifies the user’s button press. The Control MCU then

turns on power, by way of block 1, to the Communications MCU. This is accomplished

by the use of a transistor set which is designed to allow enough current for the

operation. The block 2 route is held off in this phase. Once the Communications MCU

is on, it turns on power to the WiFly WLAN unit and sends a logic 1 to the enable

switch so that it may write to the SD card. After data is sent from the electronic class

schedule’s Network File Server (NFS) and written to the SD card, the Communications

MCU sends a write finished signal to the Control MCU. The Control MCU then cuts

power to route 1 effectively turning off the Communications MCU, the WiFly WLAN,

and the enable write signal. It then gives power to route 2, by use of another

transistor set, turning on the electronic picture frame and the enable read signal so

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Cypress Semiconductor CY8C21534 Spécifications Page 27