28478G-18 Mindspeed Technologies, 28478G-18 Datasheet - Page 142

• Manufacturer Part Number: 28478G-18
• Description: Multichannel Synchronous Communications Controller 208-Pin BGA
• Manufacturer: Mindspeed Technologies

Specifications of 28478G-18

• Package: 208BGA
• Maximum Data Rate: 32768 Kbps
• Transmission Media Type: Wire
• Power Supply Type: Analog
• Typical Supply Current: 250 mA
• Typical Operating Supply Voltage: 3.3 V
• Minimum Operating Supply Voltage: 3 V
• Maximum Operating Supply Voltage: 3.6 V

message, what to do between messages, and the location of message data buffers in memory to use for transmit
data or receive data.
6.3.16.1
The following describes what MUSYCC does when the transmit channel is activated:
1. Reads the Tx Head Pointer for the channel from shared memory, and stores it in the Internal Channel
2. Reads the Message Descriptor pointed to by Tx Head Pointer, and stores it in Internal Channel Descriptor
3. Checks bit field OWNER and NP in Buffer Descriptor.
4. Checks bit field INHTBSD in Group Configuration Descriptor.
5. At end of message, Interrupt Descriptors and Buffer Status Descriptors can be written out to shared memory
6. Read Next Message Descriptor.
7. Go to 3.
6.3.16.2
The following describes what MUSYCC does when the receive channel is activated:
1. Reads the Rx Head Pointer for the specified channel from shared memory, and stores in the Internal Channel
2. Reads the Message Descriptor pointed to by Head Pointer, and stores in the Channel Descriptor map.
3. Check bit field OWNER and NP in Buffer Descriptor.
4. Check bit field INHRBSD in Group Configuration Descriptor.
28478-DSH-002-E
Descriptor map.
map.
If OWNER = 1, MUSYCC is the buffer owner. Load Channel Descriptor map with data buffer pointer and data
buffer length. Go to 4.
If OWNER = 0, MUSYCC is not the buffer owner. Can enter polling mode until MUSYCC owns buffer or
receives another service request to activate channel or jump to new message. Repeat 3.
If INHTBSD = 0 (i.e., MUSYCC is allowed to overwrite Buffer Descriptor with a Buffer Status Descriptor), the
address of the Buffer Descriptor is stored in the Message Pointer slot in shared memory. After the current
message is completely processed, MUSYCC reads in the Next Message Pointer and overwrites Buffer
Descriptor. Go to 3.
If INHTBSD = 1 (i.e., MUSYCC is not allowed to overwrite Buffer Descriptor), the address of Next Message
Pointer is pre-fetched from the current Message Descriptor and stored in the Message Pointer slot in shared
memory. After the current message is completely processed, MUSYCC jumps to this pointer and starts
processing a new message.
Go to 5 when current message is processed, otherwise repeat 4.
Simultaneously, MUSYCC masters the PCI bus and reads data into transmit FIFO from shared memory, and
the serial port outputs data using the control lines TCLK, TSYNC, and TDAT as appropriate.
(see 3)—depending on the masking of interrupts and allowance of Buffer Descriptor overwrites.
Descriptor map.
If OWNER = 0, MUSYCC is the buffer owner. Load Channel Descriptor map with data buffer pointer and data
buffer length. Go to 4.
If OWNER = 1, MUSYCC is not the buffer owner. May enter polling mode until MUSYCC owns buffer or
receives another service request to activate channel. Repeat 3.
If INHRBSD = 0 (i.e., MUSYCC is allowed to overwrite Buffer Descriptor with a Buffer Status Descriptor), the
address of the Buffer Descriptor is stored in the Message Pointer slot in shared memory. After current message
is completely processed, MUSYCC reads in Next Message Pointer and overwrites Buffer Descriptor. Go to 3.
Transmit Channel Activation
Receive Channel Activation
Preliminary Information / Mindspeed Proprietary and Confidential
Mindspeed Technologies
®
Basic Operation
129