MCIMX27 Motorola Semiconductor Products, MCIMX27 Datasheet - Page 24

• Manufacturer Part Number: MCIMX27
• Manufacturer: Motorola Semiconductor Products

Functional Description and Application Information
can work in Normal mode operation using frame sync, and in Network mode operation allowing multiple
devices to share the port with as many as thirty-two time slots.
The SSI provides two sets of Transmit and Receive FIFOs. Each of the four FIFOs is 8 × 24 bits. The two
sets of Tx/RX FIFOs can be used in Network mode to provide two independent channels for transmission
and reception. It also has programmable data interface modes such as I2S, LSB, and MSB aligned and
programmable word lengths. Other program options include frame sync, clock generation, and
programmable I2S modes (Master, Slave, or Normal). Oversampling clock, ccm_ssi_clk is available as
output from SRCK in I2S Master mode.
In addition to AC97 support, the SSI has completely separate clock and frame sync selections for the
receive and transmit sections. In the AC97 standard, the clock is taken from an external source and frame
sync is generated internally. The SSI also has a programmable internal clock divider and Time Slot Mask
registers for reduced CPU overhead (for Tx and RX both).
2.3.35
The i.MX27 processor contains six UART modules. Each UART module is capable of standard RS-232
non-return-to-zero (NRZ) encoding format and IrDA-compatible infrared modes. The UART provides
serial communication capability with external devices through an RS-232 cable or through use of external
circuitry that converts infrared signals to electrical signals (for reception); or it transforms electrical signals
to signals that drive an infrared LED (for transmission) to provide low-speed IrDA compatibility.
The UART transmits and receives characters that are either 7 or 8 bits in length (program selectable). To
transmit, data is written from the peripheral data bus to a 32-byte transmitter FIFO (TxFIFO). This data is
passed to the shift register and shifted serially out on the transmitter pin (TXD). To receive, data is received
serially from the receiver pin (RXD) and stored in a 32-half-word-deep receiver FIFO (RxFIFO). The
received data is retrieved from the RxFIFO on the peripheral data bus. The RxFIFO and TxFIFO generate
maskable interrupts as well as DMA requests when the data level in each of the FIFO reaches a
programmed threshold level.
The UART generates baud rates based on a programmable divisor and input clock. The UART also
contains programmable auto baud detection circuitry to receive 1 or 2 stop bits as well as odd, even, or no
parity. The receiver detects framing errors, idle conditions, BREAK characters, parity errors, and overrun
errors.
2.3.36
The i.MX27 processor provides three USB ports. The USB module provides high performance USB
On-The-Go (OTG) functionality, compliant with the USB 2.0 specification, the OTG supplement, and the
ULPI 1.0 Low Pin Count specification. The module consists of three independent USB cores, each
controlling one USB port.
In addition to the USB cores, the USB module provides for Transceiverless Link (TLL) operation on host
Ports 1 and 2, and provides the ability of routing the OTG transceiver interface to Host Port 1 such that
this transceiver can be used to communicate with a USB peripheral connected to Host Port 1. The USB
module has two connections to the CPU bus—one IP-bus connection for register accesses and one
AHB-bus connection for the DMA transfer of data to and from the FIFOs.
24
Universal Asynchronous Receiver/Transmitter (UART)
Universal Serial Bus (USB)
i.MX27 Data Sheet, Advance Information, Rev. 0.1
Preliminary—Subject to Change Without Notice
Freescale Semiconductor