ESIRSON(tsm)
Comparator Output
Internal Latch
ESISTOP(tsm)
ESIOUTx/
ESITCHOUTx
Time
AFE1
ESI Operation
972
SLAU367P – October 2012 – Revised April 2020
Copyright © 2012–2020, Texas Instruments Incorporated
Extended Scan Interface (ESI)
Table 37-2. Selected Output Bits
TESTDX
ESICHx(tsm)
ESITESTS1(tsm)
Selected Output Bit
0
00
X
ESIOUT0 and ESIOUT4
0
01
X
ESIOUT1 and ESIOUT5
0
10
X
ESIOUT2 and ESIOUT6
0
11
X
ESIOUT3 and ESIOUT7
1
X
0
ESITCHOUT0
1
X
1
ESITCHOUT1
When TESTDX = 0, the ESICHx(tsm) signals select which ESICIx or ESICHx channel is excited and
connected to the comparator. The ESICHx(tsm) signals also select the corresponding output bit for the
comparator result.
When TESTDX = 1, channel selection depends on the ESITESTS1(tsm) signal. When TESTDX = 1 and
ESITESTS1(tsm) = 0, input channel selection is controlled with the ESITCH0x bits and the output bit is
ESITCHOUT0. When TESTDX = 1 and ESITESTS1(tsm) = 1, input channel selection is controlled with
the ESITCH1x bits and the output bit is ESITCHOUT1.
When AFE1's ESICA1X = 1, the ESICSEL and ESICI3 bits select between the ESICIx channels and the
ESICI input, allowing storage of the comparator output for one input signal into the four output bits
ESIOUT0 to ESIOUT3. This can be used to observe the envelope function of sensors.
The output logic is enabled by the ESIRSON(tsm) signal. When a comparator output is high while
ESIRSON = 1, an internal latch is set. Otherwise the latch is reset. The latch output is written into the
selected output bit with the rising edge of the ESISTOP(tsm) signal as shown in
.
Figure 37-6. Analog Front-End Output Timing
37.2.1.6 Comparator and DAC
The analog input signals are converted into digital signals by the comparator and the programmable 12-bit
DAC. The comparator compares the selected analog signal to a reference voltage generated by the DAC.
If the voltage is above the reference, the comparator output is high. Otherwise, it is low. The comparator
outputs of both analog front-ends can be individually inverted by setting ESICA1INV for AFE1 or
ESICA2INV for AFE2. The comparator output is stored in the selected output bit and processed by the
processing state machine to detect motion and direction.