PDSP16540

The PDSP16540 Bucket Buffer is for use in systems which require a reservoir in which a block of data is accumulated,whilst previous data is being transferred to other system elements and then processed. It thus prevents the loss of incoming data whilst the previous block is being processed.Like a FIFO all address are generated internally.It differs from a normal FIFO, however, by allowing the user to define both the length of the data block and also the amount of the old data to be re-read before the new data is added.The latter feature supports the block overlapping requirements of Digital Signal Processing Systems performing Fast Fourier Transforms. PDSP16540 also provides wide, 32 bit, input and output buses, unlike normal byte wide FIFO's. This wide configuration supports the16 bit real and imaginary components of the complex data found in many DSP systems.

In particular, the device can be directly connected to the PDSP16540 FFT Processor without any external logic. The FFT Processor requires the support of an input buffer when 1024 point transforms are to be continuously performed and no incoming data is to remain un-processed.

The number of words, which are read as a complete block, can be programmed in multiples of 32 up to a maximum of 1024. The amount of new data in this block can separately be programmed in multiples of 32 words. In this manner the percentage of new data in a complete block is under the control of the user, and the PDSP16540 is not restricted to only supporting the requirements of the PDSP16510.A Read Me Flag is raised at a user defined point during the loading of new data. This allows the next system component to prepare PDSP16540 to accept data. Data is not actually transferred, however, until all the user defined amount of new data has been loaded, and a Data Available Flag goes active.The gap between the two flags can be programmed to provide sufficient time to prepare the device which is to accept data from the buffer. This provide a much more flexible solution than the simple Full Flag offered by a standard FIFO.