CTI MPG401, Руководство пользователя

Страница: 10 / 22

Mini PCIe ADC
Users Guide
www.connecttech.com
Document: CTIM-00149
Revision: 0.02 Page 10 of 22
Connect Tech Inc. 800-426-8979 | 519-836-1291
Date: 2018-10-25
Analog Inputs (ADCs)
Overview
The Mini PCIe ADC uses two Texas Instruments ADS8688, each having an 8-channel multiplexer that allows
for the sampling of 8 single ended analog signals. The SPI interface of each ADS8688 is connected to the
FPGA controller, while the analog side is connected to the high density latching connector.
The ADC IC datasheet can be found here: http://www.ti.com/lit/gpn/ads8688
Connectors & Jumpers
Function Analog Inputs
Location P1
Type Molex 501190-2017 (Pico-clasp 2x10)
Mate Molex 501189-2010 with 501193-3000
Pinout Pin Description Pin Description
1 ADC0_CH0 2 ADC0_CH1
3 ADC0_CH2 4 ADC0_CH3
5 GND 6 GND
7 ADC0_CH4 8 ADC0_CH5
9 ADC0_CH6 10 ADC0_CH7
11 ADC1_CH0 12 ADC1_CH1
13 ADC1_CH2 14 ADC1_CH3
15 ADC1_CH4 16 ADC1_CH5
17 GND 18 GND
19 ADC1_CH6 20 ADC1_CH7
Operation
The ADCs are controlled and have their data stored in two controller blocks. The mode of capture can be set
to either
Continuous Sampling Mode or Waveform Capture Mode . The input range for each of the 4 ADCs
can be changed via the INPUT_RANGE_SELECT register.
Each ADC block can be set to capture up to 8 channels in a looping sequential order. For example, if all eight
channels were enabled in ADC0 (writing 0xFF to CONTROL_CONFIG register) then the following shows the
process it would go through in obtaining the requested samples:
By default, sample collection occurs at the maximum sampling rate of the ADC IC which is 500ksps, so if, in
continuing the previous example, all 8 channels were to be enabled then the actual sampling rate per ADC
Channel would be 500ksps/8=62.5ksps.
20 2
1 19
C
H C
H C
H C
H C
H C
H C
H