at85c51snd3 ATMEL Corporation, at85c51snd3 Datasheet - Page 200

• Manufacturer Part Number: at85c51snd3
• Description: At85c51snd3 Single-chip Digital Audio Decoder - Encoder With Usb 2.0 Interface
• Manufacturer: ATMEL Corporation

DFC Data Reading
C51 Data Reading
Figure 93. Data Stream Reception Flows
200
AT85C51SND3B
read 8 data from MMDAT
a. Polling mode
STOP Command
Start Reception
Data Stream
FIFO Reading
No More Data
To Receive?
Reception
DATEN = 1
FIFO Full?
HFRS = 1?
Send
from such situation. In case of time-out, the data controller and its internal state machine
may be reset by setting and clearing the DCR bit in MMCON2 register.
This time-out may be disarmed after receiving 8 data (HFRS flag set) or after receiving
end of frame (EOFI flag set) in case of block length less than 8 data (1, 2 or 4).
In case the data transfer is handled by the DFC, a DFC channel must be configured with
the MMC controller as source peripheral. The programmed number of data is autono-
mously transferred from the FIFO to the destination peripheral without any intervention
from the firmware.
In case both FIFO are full (e.g. destination peripheral busy), card clock is automatically
frozen stopping card data transfer thanks to the controller automatic flow control.
In case the data transfer is handled by the C51
FIFO by reading MMDAT register. Each time FIFO becomes full or half full (WFRI or
HFRI set), software is requested to flush this FIFO by reading 16 or 8data.
In case FIFO is full, card clock is automatically frozen stopping card data transfer thanks
to the controller automatic flow control.
Note:
1. An enabled DFC transfer always takes precedence on a C51 transfer, it is under soft-
ware responsibility not to read from MMDAT register while a DFC transfer is enabled.
Unmask FIFO Full
Start Reception
Data Stream
Initialization
DATEN = 1
HFRM = 0
b. Interrupt mode
(1)
, data is read byte by byte from the
read 8 data from MMDAT
STOP Command
Reception ISR
Mask FIFO Full
Data Stream
FIFO Reading
No More Data
To Receive?
FIFO Full?
HFRI = 1?
HFRM = 1
Send
7632D–MP3–01/07