AT89C5132
Table 50. Sample Duplication Factor
DUP1
DUP0
Factor
0
0
1
1
0
1
0
1
No sample duplication, DAC rate = 8 kHz (C51 rate).
One sample duplication, DAC rate = 16 kHz (2 x C51 rate).
Two samples duplication, DAC rate = 32 kHz (4 x C51 rate).
Three samples duplication, DAC rate = 48 kHz (6 x C51 rate).
14.5 Interrupt Request
The audio interrupt request can be generated by two sources when in C51 audio mode: a sam-
ple request when SREQ flag in AUDSTA register is set to logic 1, and an under-run condition
when UDRN flag in AUDSTA register is set to logic 1. Both sources can be enabled separately
by masking one of them using the MSREQ and MUDRN bits in AUDCON1 register. A global
enable of the audio interface is provided by setting the EAUD bit in IEN0 register.
The interrupt is requested each time one of the two sources is set to one. The source flags are
cleared by writing some data in the audio buffer through AUDDAT, but the global audio interrupt
flag is cleared by hardware when the interrupt service routine is executed.
Figure 14-5. Audio Interface Interrupt System
UDRN
AUDSTA.6
Audio
Interrupt
Request
MUDRN
AUDCON1.4
SREQ
AUDSTA.7
EAUD
IEN0.6
MSREQ
AUDCON1.5
14.6 Voice or Sound Playing
In voice or sound playing mode, the operations required are to configure the PLL and the audio
interface according to the DAC selected. The audio clock is programmed to generate the 256·Fs
or 384·Fs. The data flow sent by the C51 is then regulated by interrupt and data is loaded 4
Bytes by 4 Bytes. Figure 14-6 shows the configuration flow of the audio interface when in voice
or sound mode.
63
4173E–USB–09/07
ATMEL [ ATMEL ]
