PNX1501E NXP Semiconductors, PNX1501E Datasheet - Page 505

• Manufacturer Part Number: PNX1501E
• Description: Digital Signal Processors & Controllers (DSP, DSC) MEDIA PROCESSOR PNX15XX/266MHZ
• Manufacturer: NXP Semiconductors

Specifications of PNX1501E

• Product: DSPs
• Maximum Operating Temperature: + 85 C
• Mounting Style: SMD/SMT
• Package / Case: SOT-795
• Minimum Operating Temperature: 0 C
• Lead Free Status / Rohs Status: Details
• Other names: PNX1501E,557

Philips Semiconductors
Volume 1 of 1
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Product data sheet
2.3.1 TRANS_ENABLE
2.3 Audio Out Data DMA Operation
Upon reset, transmission is disabled (TRANS_ENABLE = 0), and buffer 1 in memory
is the active buffer (BUF1_ACTIVE = 1). The system software initiates transmission
by providing two equal size buffers in memory (filled with valid audio data) and putting
the base addresses and sample size in the two AO_BASEx registers and the
AO_SIZE register. Once two valid buffers are assigned, transmission can be enabled
by writing a ‘1’ to TRANS_ENABLE. Note that serial frame configurations should not
be changed when transmission is enabled. The Audio Out unit hardware now
proceeds to empty buffer 1 in memory by transmission of output samples. The buffers
in memory are requested in blocks of up to 1024 32-bit word maximums. When buffer
1 in memory is empty, BUF1_EMPTY is asserted, and transmission continues without
interruption from buffer 2 in memory. If BUF1_INTEN is enabled, a level triggered
system interrupt request is generated.
Note that the buffers in memory must be 64-byte aligned (the six LSBs of AO_BASE1
and AO_BASE2 are zero). Memory buffer sizes must be in multiples of 64 samples
(the six LSBs of AO_SIZE are zero).
The system software is required to assign a new, full buffer to AO_BASE1 and
perform an ACK1 before buffer 2 in memory is empty. Transmission continues from
buffer 2 in memory until it is empty. At that time, BUF2_EMPTY is asserted, and
transmission continues from the new buffer 1 in memory.
An ACKx by the interrupt service routine performs two functions:
The TRANS_ENABLE bit of the AO_CTL register controls the transfer of data from
memory and the transmission of data from the serial output pins. While this control bit
is enabled, configuration parameters in the register set should not be changed.
When TRANS_ENABLE is disabled after it had been enabled, an abort is sent out to
the DMA interface adapter to cancel all DMA transactions associated with the Audio
Out and serial transmission as well as WS transmission is stopped.
Before enabling the TRANS_ENABLE bit after an enable, disable sequence, care
must be taken that the correct address values are stored in the base address
registers. Upon a restart of TRANS_ENABLE, DMA transfers will start from the
address given by AO_BASE1. In some modes, a restart of existing values of the base
address registers may not produce coherent results.
When TRANS_ENABLE is disabled after a period of being enabled, the status flags
for BUF1_ACTIVE, UNDERRUN, HBE, BUF2_EMPTY and BUF1_EMPTY within the
AO_STATUS register will retain the values they were at when the disable effect took
place. If the TRANS_ENABLE is enabled once again, these flags will be reset to their
initial states by the hardware before starting up transmission again.
•
•
It notifies Audio Out that the corresponding AO_BASEx register now points to a
buffer filled with samples.
It clears BUFx_EMPTY. Upon receipt of an ACKx, the Audio Out hardware
de asserts the interrupt request line at the next system controller clock edge.
Rev. 2 — 1 December 2004
© Koninklijke Philips Electronics N.V. 2002-2003-2004. All rights reserved.
PNX15xx Series
Chapter 15: Audio Output
15-5