A0 -A5 Constraints in Arty 7

[Ahmed Alfadhel]

Hi @jpeyron,

According to the constraints file provided by Diligent, pins  A0 - A5 each one  is allocated a dual constraint. Why dual n & p ? 

if n for negative, we can connect to GND pin.

__________________________________________________________________________________________________________

##ChipKit Single Ended Analog Inputs
##NOTE: The ck_an_p pins can be used as single ended analog inputs with voltages from 0-3.3V (Chipkit Analog pins A0-A5). 
##      These signals should only be connected to the XADC core. When using these pins as digital I/O, use pins ck_io[14-19].

#set_property -dict { PACKAGE_PIN C5    IOSTANDARD LVCMOS33 } [get_ports { ck_an_n[0] }]; #IO_L1N_T0_AD4N_35 Sch=ck_an_n[0]
#set_property -dict { PACKAGE_PIN C6    IOSTANDARD LVCMOS33 } [get_ports { ck_an_p[0] }]; #IO_L1P_T0_AD4P_35 Sch=ck_an_p[0]
#set_property -dict { PACKAGE_PIN A5    IOSTANDARD LVCMOS33 } [get_ports { ck_an_n[1] }]; #IO_L3N_T0_DQS_AD5N_35 Sch=ck_an_n[1]
#set_property -dict { PACKAGE_PIN A6    IOSTANDARD LVCMOS33 } [get_ports { ck_an_p[1] }]; #IO_L3P_T0_DQS_AD5P_35 Sch=ck_an_p[1]
#set_property -dict { PACKAGE_PIN B4    IOSTANDARD LVCMOS33 } [get_ports { ck_an_n[2] }]; #IO_L7N_T1_AD6N_35 Sch=ck_an_n[2]
#set_property -dict { PACKAGE_PIN C4    IOSTANDARD LVCMOS33 } [get_ports { ck_an_p[2] }]; #IO_L7P_T1_AD6P_35 Sch=ck_an_p[2]
#set_property -dict { PACKAGE_PIN A1    IOSTANDARD LVCMOS33 } [get_ports { ck_an_n[3] }]; #IO_L9N_T1_DQS_AD7N_35 Sch=ck_an_n[3]
#set_property -dict { PACKAGE_PIN B1    IOSTANDARD LVCMOS33 } [get_ports { ck_an_p[3] }]; #IO_L9P_T1_DQS_AD7P_35 Sch=ck_an_p[3]
#set_property -dict { PACKAGE_PIN B2    IOSTANDARD LVCMOS33 } [get_ports { ck_an_n[4] }]; #IO_L10N_T1_AD15N_35 Sch=ck_an_n[4]
#set_property -dict { PACKAGE_PIN B3    IOSTANDARD LVCMOS33 } [get_ports { ck_an_p[4] }]; #IO_L10P_T1_AD15P_35 Sch=ck_an_p[4]
#set_property -dict { PACKAGE_PIN C14   IOSTANDARD LVCMOS33 } [get_ports { ck_an_n[5] }]; #IO_L1N_T0_AD0N_15 Sch=ck_an_n[5]
#set_property -dict { PACKAGE_PIN D14   IOSTANDARD LVCMOS33 } [get_ports { ck_an_p[5] }]; #IO_L1P_T0_AD0P_15 Sch=ck_an_p[5]
 

 

thanks.

[jpeyron]

Hi @Ahmed Alfadhel,

On page 3 of the schematic it shows that the negative signals are tied to ground for A0-A5. For more information on how to use the XADC on the Arty-A7-35T here is a verilog XADC project. Here is the WIKI for the  Arty A7-35T XADC demo.

cheers,

Jon