Datasheet

Module Operation

www.ti.com

24.2.1 Data Transfers between Main RAM and NHET RAM

24.2.1.1 Addressing Modes

The addressing modes of a control packet need to be distinguished between the main RAM of the CPU

and the NHET RAM.

Main RAM

For each double control packet (see Section 24.2.1.3) the addressing mode for the main RAM (RAM0/1)

can be configured to constant or post-increment mode in register IHADDRCT.

• Constant Addressing: In constant mode, the HTU writes/reads the data to/from the same address in

the main RAM.

• Post-increment Addressing: In post-increment mode, the HTU writes/reads the data to/from the main

RAM by incrementing through the addresses after each transfer. If 32-bit transfers are selected it will

automatically increment by 4 Byte, if 64-bit transfers are selected, it will increment by 8 Byte. The

examples of Use Cases illustrate the post-increment mode, where the elements of consecutive frames

are transferred to/from consecutive locations in the main RAM buffer.

NHET RAM

How a DCP addresses the NHET RAM is determined by the initial NHET address, the initial element

counter (IETCOUNT) and the NHET addressing mode (ADDMH). The main difference to the main RAM

addressing mode is that the HET address is reset to the initial HET address for every first element of a

frame. To implement constant addressing, the initial element counter needs to be set to 1. Post-increment

addressing is selected by programming the initial element counter to a value other than 1.

24.2.1.2 Single Buffer Implementation

In a single buffer implementation, the DCP is set up to transfer data to/from a single buffer in the main

RAM. With each transfer request, the programmed number of elements is transferred and the buffer

pointer is reset to its starting address after the programmed number of frame transfers have completed.

Figure 24-4 shows the request on one request line of the HTU and the frame running on the assigned

control packet visualized by the element counter. In the diagram, the frame has 5 element transfers

(element count = 5).

1068

High-End Timer Transfer Unit (HTU) Module SPNU562–May 2014

Submit Documentation Feedback