SSI Operating Modes
MOTOROLA
Synchronous Serial Interface (SSI)
30-39
30.5.1 Normal Mode
Normal mode is the simplest mode of the SSI. It transfers one word per frame. In continuous clock mode, a
frame sync occurs at the beginning of each frame. The length of the frame is determined by the fields of the
STCCR or SRCCR registers:
•
The period of the serial bit clock. For external clocking, this is based on the frequency on the
SSI_TXCLK pin. For an internal clock, this is determined by the values of the PSR bit and the PM
field.
•
The number of bits per sample (WL)
•
The number of time slots per frame (DC)
When normal mode is configured to provide more than one time slot per frame, data is transmitted only in
the first time slot. No data is transmitted in subsequent time slots.
30.5.1.1 Normal Mode Transmit
The conditions for data transmission from the SSI in normal mode are:
1. SSI enabled (SCSR:SSI_EN
=
1)
2. Enable the FIFO (STCR:TFEN
=
1) and configure the transmit (SFCSR:TFWM) and
receive (SFCSR:RFWM) Water Marks if the FIFO is used.
3. Write data to the STX register
4. Enable transmitter (SCSR:TE
=
1)
5. Active frame sync (required for continuous clock)
6. Active bit clock (the bit clock is active when the transmitter is enabled; for a gated clock,
see Table 30-14)
When these conditions occur in normal mode, the next data word is transferred into the TXSR. When the
transmit FIFO is enabled, the data word is transferred from the transmit FIFO. When the transmit FIFO is
disabled, the data word is transferred from the STX register.
The new data word is transmitted immediately and the TDE bit is set.
When the transmit FIFO is disabled and the TIE bit in the STCR is set, the transmit interrupt occurs. When
the transmit FIFO is enabled, the FIFO waits until the Transmit Water Mark level has been reached. The
transmit interrupt then occurs if the TIE bit is set. In this case, an eighth data word is transferred and
shifted out before the MC9328MX1 writes new data to the STX register.
The SSI_TXDAT pin is disabled except during the data transmission period. For a continuous clock, the
optional frame sync output and clock outputs are not tri-stated, even when both receiver and transmitter are
disabled.
30.5.1.2 Normal Mode Receive
The conditions for data reception from the SSI are:
1. SSI enabled (SCSR:SSI_EN
=
1)
2. Receiver enabled (SCSR:RE
=
1)
3. Active frame sync (required for continuous clock)
4. Active bit clock (the bit clock is active when the receiver is enabled; for a gated clock, see
Table 30-14)
Summary of Contents for DragonBall MC9328MX1
Page 68: ...1 12 MC9328MX1 Reference Manual MOTOROLA Introduction ...
Page 86: ...2 18 MC9328MX1 Reference Manual MOTOROLA Signal Descriptions and Pin Assignments ...
Page 116: ...3 30 MC9328MX1 Reference Manual MOTOROLA Memory Map ...
Page 126: ...4 10 MC9328MX1 Reference Manual MOTOROLA ARM920T Processor ...
Page 160: ...8 8 MC9328MX1 Reference Manual MOTOROLA System Control ...
Page 272: ...13 32 MC9328MX1 Reference Manual MOTOROLA DMA Controller ...
Page 281: ...Programming Model MOTOROLA Watchdog Timer Module 14 9 ...
Page 282: ...14 10 MC9328MX1 Reference Manual MOTOROLA Watchdog Timer Module ...
Page 300: ...15 18 MC9328MX1 Reference Manual MOTOROLA Analog Signal Processor ASP ...
Page 438: ...18 16 MC9328MX1 Reference Manual MOTOROLA Serial Peripheral Interface Modules SPI 1 and SPI 2 ...
Page 478: ...19 40 MC9328MX1 Reference Manual MOTOROLA LCD Controller ...
Page 574: ...21 32 MC9328MX1 Reference Manual MOTOROLA Memory Stick Host Controller MSHC Module ...
Page 598: ...23 16 MC9328MX1 Reference Manual MOTOROLA Real Time Clock RTC ...
Page 670: ...24 72 MC9328MX1 Reference Manual MOTOROLA SDRAM Memory Controller ...
Page 726: ...25 56 MC9328MX1 Reference Manual MOTOROLA SmartCard Interface Module SIM ...
Page 736: ...26 10 MC9328MX1 Reference Manual MOTOROLA General Purpose Timers ...
Page 854: ...29 18 MC9328MX1 Reference Manual MOTOROLA I2C Module ...
Page 900: ...30 46 MC9328MX1 Reference Manual MOTOROLA Synchronous Serial Interface SSI ...
Page 942: ...32 26 MC9328MX1 Reference Manual MOTOROLA GPIO Module and I O Multiplexer IOMUX ...