Digital Interface
4
Digital Interface
Connector J19 (Samtec part number ERF8-025-01-L-D-RZ-L-TR socket strip connector) provides the
digital I/O connections between the ADS86xxEVM board and the simple capture card. Consult Samtec at
or call 1-800-SAMTEC-9 for a variety of mating connector options.
summarizes
the pin outs for connector J19.
Table 9. Connector J19 Pin Out
Pin Number
Signal
Description
J19.1
DAISY
Daisy input for the ADC
J19.4
EVM_PRESENT
EVM present, active low (connected to GND)
J19.5
REFSEL
Reference selection input for the ADC
J19.6
RST/PD
Reset or power-down input for the ADC
J19.8
A
No connection
J19.11
EVM_ID_SDA
I
2
C data for the onboard EEPROM
J19.12
EVM_ID_SCL
I
2
C clock for the onboard EEPROM
J19.13
3V3_SDCC
3.3-V digital supply from the simple capture card
J19.14
5V_SDCC
Unregulated 5-V supply from the simple capture card
J19.33, J19.34
SCLK
Clock input for the ADC
J19.35
CS
Chip-select input for the ADC
J19.38
SDI
Data input for the ADC
J19.39
SDO
Data output from the ADC
Digital connections for the onboard micro secure digital
J19.45-49
EVMSDxxxxx
(microSD) card
J19.2, J19.10, J19.16, J19.50
GND
Ground connections
4.1
Serial Interface (SPI)
The ADS86xx device uses SPI serial communication in mode 1 (CPOL = 0, CPHA = 1) with clock speeds
up to 18 MHz. The ADS86xxEVM offers 49.9-
Ω
resistors between the SPI signals and J19 to aid with
signal integrity. Typically, in high-speed SPI communication, fast signal edges can cause overshoot; these
49.9-
Ω
resistors slow down the signal edges in order to minimize signal overshoot.
4.2
I
2
C Bus for the Onboard EEPROM
The ADS86xxEVM has an I
2
C bus that records the board name and assembly date to communicate with
the onboard EEPROM. The bus is not used in any form by the ADS86xx converter.
4.3
microSD Card
The ADS86xxEVM has a microSD card that contains the software files for the simple capture card. The
contents of the microSD card must not be deleted or altered.
9
SBAU245A – June 2015 – Revised July 2015
ADS86xxEVM-PDK Evaluation Module
Copyright © 2015, Texas Instruments Incorporated