____________________________________________________ DS34T101, DS34T102, DS34T104, DS34T108
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Table 9-9. CPU Interface Pins
PIN DESCRIPTION
H_CPU_SPI_N
Ipu
Host Bus Interface
0 = SPI serial interface
1 = Parallel interface
DAT_32_16_N
Ipu
Data Bus Width
0 = 16-bit
1 = 32-bit
In SPI bus mode this pin is ignored.
H_D[31:1]
IO
8mA
Host Data Bus
When the device is configured for a 32-bit parallel interface, H_D[31:0] are the
data I/O pins (HD[31] is the MSb). When the device is configured for a 16-bit
parallel interface, H_D[15:0] are the data I/O pins (HD[15] is the MSb) and
H_D[31:16] are ignored and should be pulled low or high. The
DAT_32_16_N pin
specifies bus width. In SPI bus mode these pins are ignored.
H_D[0] /
SPI_MISO
IO
8mA
H_D[0]: Host Data LSb
In parallel interface mode this pin is H_D[0], LSb of the data bus.
SPI_MISO: SPI Data Output (Master In Slave Out)
In SPI bus mode this pin is the SPI data output.
H_AD[24:1]
I
Host Address Bus
H_AD[24] is the MSb. When the host data bus is 32 bits (
DAT_32_16_N=1),
H_AD[1] should be held low. In SPI bus mode these pins are ignored.
H_CS_N
I
Host Chip Select (Active Low)
In parallel interface mode this pin must be asserted (low) to read or write internal
registers. In SPI bus mode this pin is ignored.
H_R_W_N /
SPI_CP
I
H_R_W_N: Host Read/Write Control
In parallel interface mode this pin controls whether an access to internal registers
is a read or a write.
SPI_CP: SPI Clock Phase
In SPI interface mode this pin specifies SPI clock phase. See the timing diagrams
0 = input data is latched on the leading edge of the SCLK pulse; output data is
updated on the trailing edge
1 = input data is latched on the trailing edge of the SCLK pulse; output data is
updated on the leading edge
H_WR_BE0_N /
SPI_CLK
I
H_WR_BE0_N: Host Write Enable Byte 0 (Active Low)
In parallel interface mode during a write access this pin specifies whether or not
byte 0
(H_D[7:0]) should be written to the device. This pin is active in both 32-bit
and 16-bit modes.
0 = write byte 0
1 = don’t write byte 0
SPI_CLK: SPI Clock
In SPI interface mode this pin is the clock for the interface.
H_WR_BE1_N /
SPI_MOSI
I
H_WR_BE1_N: Host Write Enable Byte 1 (Active Low)
In parallel interface mode during a write access this pin specifies whether or not
byte 1
(H_D[15:8]) should be written to the device. This pin is active in both 32-bit
and 16-bit modes.
0 = write byte 1
1 = don’t write byte 1
SPI_MOSI: SPI Data Input (Master Out Slave In)
In SPI interface mode this pin is the data input pin for the interface.