sca100t VTI Hamlin, sca100t Datasheet - Page 11

• Manufacturer Part Number: sca100t
• Description: The Sca100t Dual Axis Inclinometer Series
• Manufacturer: VTI Hamlin

VTI Technologies Oy
www.vti.fi
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SPI command can be either an individual command or a combination of command and data. In the
case of combined command and data, the input data follows uninterruptedly the SPI command and
the output data is shifted out parallel with the input data.
The SPI interface uses an 8-bit instruction (or command) register. The list of commands is given in
Table below.
Measure mode (MEAS) is standard operation mode after power-up. During normal operation, the
MEAS command is the exit command from Self test.
Read temperature data register (RWTR) reads temperature data register during normal
operation without affecting the operation. The temperature data register is updated every 150 µs.
The load operation is disabled whenever the CSB signal is low, hence CSB must stay high at least
150 µs prior to the RWTR command in order to guarantee correct data. The data transfer is
presented in Figure 10 below. The data is transferred MSB first. In normal operation, it does not
matter what data is written into temperature data register during the RWTR command and hence
writing all zeros is recommended.
Self test for X-channel (STX) activates the self test function for the X-channel (Channel 1). The
internal charge pump is activated and a high voltage is applied to the X-channel acceleration
Command
name
MEAS
RWTR
RDSR
RLOAD
STX
STY
RDAX
RDAY
Figure 10. Command and 8 bit temperature data transmission over the SPI
each bit is sampled on the rising edge of SCK (MOSI line)
after the device is selected with the falling edge of CSB, an 8-bit command is received. The
command defines the operations to be performed
the rising edge of CSB ends all data transfer and resets internal counter and command register
if an invalid command is received, no data is shifted into the chip and the MISO remains in
high impedance state until the falling edge of CSB. This reinitializes the serial communication.
data transfer to MOSI continues immediately after receiving the command in all cases where
data is to be written to SCA100T’s internal registers
data transfer out from MISO starts with the falling edge of SCK immediately after the last bit of
the SPI command is sampled in on the rising edge of SCK
maximum SPI clock frequency is 500kHz
maximum data transfer speed for RDAX and RDAY is 5300 samples per sec / channel
SC K
M O S I
C SB
M ISO
0
1
2
Command
format
00000000
00001000
00001010
00001011
00001110
00001111
00010000
00010001
H IG H IM PED AN C E
C O M M AN D
3
4
5
Subject to changes
Doc. nr. 8261800
6
Description:
Measure mode (normal operation mode after power on)
Read and write temperature data register
Read status register
Reload NV data to memory output register
Activate Self test for X-channel
Activate Self test for Y-channel
Read X-channel acceleration through SPI
Read Y-channel acceleration through SPI
7
7
7
8
6
6
9
10
5
5
D A TA O U T
D A T A IN
11
4
4
12
3
3
13
2
2
14
1
1
15
0
0
SCA100T Series
Rev.A
11/18