Serial Peripheral Interface to communicate with ADS7843 (Touch Panel)
Wishbone bus interface
Description
This SPI controller module is a Master Serial Peripheral Interface. In a special application it is used to communicate with the Touch Screen Controller ADS7843 (Slave) which uses a serial interface, too. A usual communication between the SPI controller and the touch controller consists of eight clock cycles. To complete a transmission between two devices with serial interfaces it can be necessary to execute several serial communication cycles.
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In case of the touch controller AD7846 a complete transmission of a data block can be accomplished with three serial communications. The SPI controller executes the transmission itself without any further intervention by a CPU.
MEN IP cores are described in standard VHDL language and the standard Wishbone bus is used as the system interface.
By using IP cores, application-specific functions can be performed flexibly and individually in the FPGA on a growing range of MEN CPU boards. These IP cores can be assembled from the MEN function library and reconfigured, combined with IP cores from other providers or even completely redeveloped as required. The FPGA behaves just like a standard PCI component. The FPGA functions are loaded by software when the system is booted and are available in less than 1 s. On PowerPC® platforms the FPGA can be dynamically updated during operation. On Pentium® platforms FPGA updates are also possible in the boot Flash during operation and are then available once the system is rebooted.
Technical Data
Size
Logic elements (Altera® Cyclone® device family): 130 typ.
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Pin count: 5
System-Bus Interface
Wishbone bus interface compliant with Wishbone Specification B.3
32-bit data transfer, 33MHz bus frequency
Supported Wishbone bus cycles
•
Single read/write
SPI Functionality
Communication with touch screen controllers ADS7843 or AD7846
SPI clock frequency variable by user via system-bus interface