2/24/2008 9T6WP
Preliminary Hardware Data Module
BCM7405
06/29/07
Functional Description
Bro a d c o m Co rp o r a ti o n
Document
7405-1HDM00-R
Peripherals Page 1-83
Figure 1-27: MCIF Interfaces
Input and Output Processes
Output To M-CARD
1
TX_BUF_PTR points to the start of the buffer where data is kept. It should contain the whole packet segment data up to
a maximum size of 4096 bytes. EC, F, and L bits are kept in TX_CTRL register.
2
The CPU sets the GO bit of the TX_CTRL register. The MCIF detects the GO register bit and starts the output operation.
3
After reading the first 256 bits from memory, the MCIF starts the actual transfer. This is done to take care of any delay
in receiving memory accesses. IQB, MSB, and LSB are sent first and then the first 256 bits of data are sent. Once the
256-bit register is empty, a memory read request is generated for every 256 bits (32 bytes) of the data until the whole
packet is transferred.
4
Once the whole buffer is read, the MCIF sets the DA to 0, clears the GO bit, and waits for the CPU to set the buffer and
issue the GO.
5
The MCIF sets the following bits in the Interrupt Status Register.
•
MRPKT
: This is set at the end of each packet read.
•
TX_DONE
: This is set once the whole packet has been transferred. The MCIF clears the GO bit at this time.
Input From M-CARD
1
The RX_BUF_PTR points to the start of the buffer. The buffer size should always be 4K bytes.
2
The MCIF sets the HR bit in the RX_STATUS register and looks for the CR from the M-CARD.
3
The M-Card issues DA as 1, EC, and length. The MCIF clocks the IQB and the length. The MCIF writes the length of the
packet to the RX_LEN register and the read-control (EC, F, L bits) to the RX_STATUS register.
4
The MCIF clocks the first 256 bits from the M-Card to a FIFO and then transfers it to a 256 bit register. The MCIF issues
a memory write request for the first 256 bits of the packet and then transfers these 256 bits to memory.
5
The MCIF issues a memory write request for the next 256 bits of the packet until all the packet has been transferred.
6
Once all the data has been transferred through the serial interface, the MCIF sets the
RX_DONE
interrupt bit and clears
the HR bit.
7
After the final data is written to memory, the
MWPKT
interrupt bit is set and the received packet information is written to
the RX_DATA_STATUS register.
M-CARD
MCIF
RBUS
SCB
CPU/PCI
IRQ
HOST
M-CARD signals