Rainbow Electronics AT89C5132 - Manual (Page 64)

64
AT8xC5132
4173A–8051–08/02
Table 66. Sample Duplication Factor
Interrupt Request The audio interrupt request can be generated by two sources when in C51 audio mode:
a sample 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 glo-
bal audio interrupt flag is cleared by hardware when the interrupt service routine is
executed.
Figure 44. Audio Interface Interrupt System
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 inter-
rupt and data is loaded 4 Bytes by 4 Bytes. Figure 45 shows the configuration flow of the
audio interface when in voice or sound mode.
DUP1 DUP0 Factor
0 0 No sample duplication, DAC rate = 8 kHz (C51 rate).
0 1 One sample duplication, DAC rate = 16 kHz (2 x C51 rate).
1 0 Two samples duplication, DAC rate = 32 kHz (4 x C51 rate).
1 1 Three samples duplication, DAC rate = 48 kHz (6 x C51 rate).
SREQ
AUDSTA.7
Audio
Interrupt
Request
UDRN
AUDSTA.6
MSREQ
AUDCON1.5
EAUD
IEN0.6
MUDRN
AUDCON1.4