UM10503
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© NXP B.V. 2012. All rights reserved.
User manual
Rev. 1.3 — 6 July 2012
430 of 1269
NXP Semiconductors
UM10503
Chapter 20: LPC43xx SD/MMC interface
20.6.19 Status Register (STATUS)
Table 315. Status Register (STATUS, address 0x4000 4048) bit description
Bit
Symbol
Description
Reset
value
0
FIFO_RX_
WATERMARK
FIFO reached Receive watermark level; not qualified with data transfer.
0
1
FIFO_TX_
WATERMARK
FIFO reached Transmit watermark level; not qualified with data transfer.
1
2
FIFO_EMPTY
FIFO is empty status
1
3
FIFO_FULL
FIFO is full status
0
7:4
CMDFSMSTATES
Command FSM states:
0 - Idle
1 - Send init sequence
2 - Tx cmd start bit
3 - Tx cmd tx bit
4 - Tx cmd index + arg
5 - Tx cmd crc7
6 - Tx cmd end bit
7 - Rx resp start bit
8 - Rx resp IRQ response
9 - Rx resp tx bit
10 - Rx resp cmd idx
11 - Rx resp data
12 - Rx resp crc7
13 - Rx resp end bit
14 - Cmd path wait NCC
15 - Wait; CMD-to-response turnaround
NOTE: The command FSM state is represented using 19 bits. The STATUS
Register(7:4) has 4 bits to represent the command FSM states. Using these 4
bits, only 16 states can be represented. Thus three states cannot be
represented in the STATUS(7:4) register. The three states that are not
represented in the STATUS Register(7:4) are:
- Bit 16 - Wait for CCS
- Bit 17 - Send CCSD
- Bit 18 - Boot Mode
Due to this, while command FSM is in Wait for CCS state or Send CCSD or
Boot Mode?, the Status register indicates status as 0 for the bit field 7:4.
0
8
DATA_3_STATUS
Raw selected card_data[3]; checks whether card is present
0 - card not present
1 - card present
9
DATA_BUSY
Inverted version of raw selected card_data[0]
0 - card data not busy
1 - card data busy
10
DATA_STATE_
MC_BUSY
Data transmit or receive state-machine is busy
1
16:11
RESPONSE_INDEX Index of previous response, including any auto-stop sent by core.
0
29:17
FIFO_COUNT
FIFO count - Number of filled locations in FIFO
0
30
DMA_ACK
DMA acknowledge signal state
0
31
DMA_REQ
DMA request signal state
0