SHARP_LH7A404 Datasheet, PDF (42/51 Pages) Sharp Electrionic Components – 32 BIT SYSTEM ON CHIP

LH7A404
32-Bit System-on-Chip
For National Semiconductor MICROWIRE format,
the serial frame pin (SSPFRM) is active LOW. Both the
SSP and external slave device drive their output data
on the falling edge of the clock, and latch data from the
other device on the rising edge of the clock. Unlike the
full-duplex transmission of the other two frame formats,
the National Semiconductor MICROWIRE format uti-
lizes a master-slave messaging technique that oper-
ates in half-duplex. When a frame begins in this mode,
an 8-bit control message is transmitted to the off-chip
slave. During this transmission no incoming data is
received by the SSP. After the message has been sent,
the external slave device decodes the message. After
waiting one serial clock period after the last bit of the 8-
bit control message was received it responds by return-
ing the requested data. The returned data can be 4 to
16 bits in length, making the total frame length between
13 to 25 bits. See Figure 22 and Figure 23.
SSPCLK
nSSPFRM
SSPTXD
MSB
8-BIT CONTROL
SSPRXD
LSB
0 MSB
LSB
4 to 16 BITS
OUTPUT DATA
Figure 22. MICROWIRE Frame Format (Single Transfer)
LH7A404-34
SSPCLK
nSSPFRM
SSPTXD LSB
MSB
SSPRXD
0 MSB
LSB
4 to 16 BITS
OUTPUT DATA
8-BIT CONTROL
LSB
MSB
Figure 23. MICROWIRE Frame Format (Continuous Transfers)
LH7A404-35
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