xe8802 Semtech Corporation, xe8802 Datasheet - Page 112

• Manufacturer Part Number: xe8802
• Description: Data Acquisition Soc With 16+10 Bit Zoomingadc? Embedded Risc Controller And Lcd Driver
• Manufacturer: Semtech Corporation

The direction of each bit within the SPI (input or input/output) can be individually set by using the RegSpiDir
register. If RegSpiDir[x] = 1, the corresponding SPI pad becomes an output. After reset (nresetpconf), the SPI
pads are in input configuration (RegSpiDir[x] are reset to 0).
In output configuration, the data are stored in RegSpiDataOut prior to output at SPI pads.
In input configuration, the status of SPI pads is available in RegSpiIn (read only). Reading is always direct –there is
no digital debounce function associated with SPI pads. In case of possible noise on input signals, a software
debouncer or an external filter must be realized.
If a bit in RegSpiPullup is set, the pull-up of the corresponding input pad is active. The pull-ups are disabled in
output configuration independently of the RegSpiPullup content. By default after reset, the SPI pads are
configured as input ports with all pull-ups active. Note that the pull-up resistors can be used for the input pads in
SPI mode also.
Next table shows the link between SPI pads and SPI data bits.
© Semtech 2006
SPI pad names
Figure 16-5: Structure of the SPI general purpose port
MOSI
MISO
vdd
NSS
SCK
Table 16-10: SPI pad/bit relationship
XE8802 Sensing Machine Data Acquisition MCU
spi_pullup[3:0]
spi_out[3:0]
spi_dir[3:0]
spi_in[3:0]
16-9
SpiDataOut[3] or SpiDataIn[3]
SpiDataOut[2] or SpiDataIn[2]
SpiDataOut[1] or SpiDataIn[1]
SpiDataOut[0] or SpiDataIn[0]
with ZoomingADC™ and LCD driver
SPI
SPI data bits
RegSpiDataOut
RegSpiPullup
RegSpiDataIn
RegSpiDir
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