Datasheet

ManualsBrandsTEXAS INSTRUMENTS ManualsDev KitsEvaluation board

2051

www.ti.com

Module Operation

The packet consists only of data bits and no header information. It can be 8-, 16- or 32-bit wide. A variable

packet width is not supported because the DMM module will check the number of incoming bits (DMMCLK

cycles) for error detection. The DMM will write the received data to the destination once the programmed

number of bits has been received.

If the programmed word width does not correspond to the received data, the following actions will be

taken:

• If the received data is greater than the programmed width, only the configured number of bits are

transferred into the RAM buffer, the additional bits are discarded.

• If the received number of bits is smaller than the programmed width, no data will be written to the

buffer, because a new DMMSYNC signal has been received before the expected number of bits.

35.2.2 Data Port

The packet will be received in several subpackets, depending on the width of the external data bus

(DMMDATA[y:0]) and the amount of data to be transmitted. Table 35-4 illustrates the number of clock

cycles required for a complete packet.

Table 35-4. Number of Clock Cycles per Packet

Write Size in Bits

Port Width/ Pins

8 16 32 64

1 32 40 56 88

2 16 20 28 44

4 8 10 14 22

8 4 5 7 11

16 2 3 4 6

The user can program the port width in the DMMPC0 register (Section 35.3.16). This feature allows pins

that are not used for DMM functionality to be used as GIO pins. Only the pins shown in Table 35-5 can be

used for a desired port width.

Table 35-5. Pins Used for Data Communication

Port Width Pins Used

1 DMMDATA[0]

2 DMMDATA[1:0]

4 DMMDATA[3:0]

8 DMMDATA[7:0]

16 DMMDATA[15:0]

NOTE: If pins other than the ones specified in Table 35-5 are programmed as functional pins for a

desired port width, the received data will be corrupted and will not be transferred to the

deserializer.

NOTE: If DMMCLK or DMMSYNC are programmed as nonfunctional pins, functional operation will

not occur.

1829

SPNU562–May 2014 Data Modification Module (DMM)

Submit Documentation Feedback