Samsung S5PC100 User Manual page 955

SD/MMC CONTROLLER
7.5 ADMA STATES
Figure 8.12-16 shows state diagram of ADMA. 4 states are defined; Fetch Descriptor state, Change Address
state, Transfer Data state, and Stop ADMA state. Operation of each state is explained in Table 8.12-3.
State Name
ST_FDS
(Fetch Descriptor)
ST_CADR
(Change Address)
ST_TFR
(Transfer Data)
ST_STOP
(Stop DMA)
ADMA does not support suspend / resume function but stop and continue are available. When the Stop At Block
Gap Request in the Block Gap Control register is set during the ADMA operation, the Block Gap Event Interrupt is
generated when ADMA is stopped at block gap. The Host Controller shall stop ADMA read operation by using
8.12-20
Figure 8.12- 16 State Diagram of the ADMA
Table 8.12- 2 ADMA States
ADMA fetches a descriptor line and set parameters in internal registers. Next
go to ST_CADR state.
Link operation loads another Descriptor address to ADMA System Address
register. In other operations, ADMA System Address register is incremented to
point next descriptor line. If End=0, go to ST_TFR state. ADMA shall not be
stopped at this state even if some errors occur.
Data transfer of one descriptor line is executed between system memory and
SD card. If data transfer continues (End=0) go to ST_FDS state. If data
transfer completes, go to ST_STOP state.
ADMA stays in this state in following cases: (1) After Power on reset or
software reset. (2) All descriptor data transfers are completed If a new ADMA
operation is started by writing Command register, go to ST_FDS state.
S5PC100 USER'S MANUAL (REV1.0)
Operation