I am trying to implement SPI interface and have been using PMOD JXADC. My host board requires 1.8V so I am using SET_VADJ and VADJ_EN for driving 1.8V. With this configuration, it works find with 15MHZ/25MHZ but sometime it doesn't work and from the logic analyzer, I am seeing data skew.
Especially pins(spi_reserve1, spi_reserve2) from JXADC bottom row(_N pins), I am seeing the problems.
1. what IOSTANDARD should I use? I am using LVCMOS18. Is that correct or can I use LVDS18?
2. According to reference manual, recommended usage is 2.5V, differential pairs, I am new to the this area so don't understand fully regarding the difference between single ended and differential. In my project,
2.1 should I use single-ended pins or differential pins? if differential is okay then a host SPI pins should support also differential pair?
Question
Zzingoh
Hi All,
I am trying to implement SPI interface and have been using PMOD JXADC. My host board requires 1.8V so I am using SET_VADJ and VADJ_EN for driving 1.8V. With this configuration, it works find with 15MHZ/25MHZ but sometime it doesn't work and from the logic analyzer, I am seeing data skew.
Especially pins(spi_reserve1, spi_reserve2) from JXADC bottom row(_N pins), I am seeing the problems.
1. what IOSTANDARD should I use? I am using LVCMOS18. Is that correct or can I use LVDS18?
## XADC Header
# 1.8V
set_property -dict { PACKAGE_PIN J14 IOSTANDARD LVCMOS18 } [get_ports { spi_clk }]; #IO_L3P_T0_DQS_AD1P_15 Sch=xa_p[1]
set_property CLOCK_DEDICATED_ROUTE FALSE [get_nets spi_clk_IBUF]
set_property -dict { PACKAGE_PIN H14 IOSTANDARD LVCMOS18 } [get_ports { spi_reset }]; #IO_L3N_T0_DQS_AD1N_15 Sch=xa_n[1]
set_property -dict { PACKAGE_PIN H13 IOSTANDARD LVCMOS18 } [get_ports { spi_cs }]; #IO_L1P_T0_AD0P_15 Sch=xa_p[2]
set_property -dict { PACKAGE_PIN G13 IOSTANDARD LVCMOS18 } [get_ports { spi_reserved1}]; #IO_L1N_T0_AD0N_15 Sch=xa_n[2]
set_property -dict { PACKAGE_PIN G15 IOSTANDARD LVCMOS18 } [get_ports { spi_miso }]; #IO_L2P_T0_AD8P_15 Sch=xa_p[3]
set_property -dict { PACKAGE_PIN G16 IOSTANDARD LVCMOS18 } [get_ports { interrupt}]; #IO_L2N_T0_AD8N_15 Sch=xa_n[3]
set_property -dict { PACKAGE_PIN J15 IOSTANDARD LVCMOS18 } [get_ports { spi_mosi }]; #IO_L5P_T0_AD9P_15 Sch=xa_p[4]
set_property -dict { PACKAGE_PIN H15 IOSTANDARD LVCMOS18 } [get_ports { spi_reserved2 }]; #IO_L5N_T0_AD9N_15 Sch=xa_n[4]
2. According to reference manual, recommended usage is 2.5V, differential pairs, I am new to the this area so don't understand fully regarding the difference between single ended and differential. In my project,
2.1 should I use single-ended pins or differential pins? if differential is okay then a host SPI pins should support also differential pair?
2.2 PMOD JXADC support V1.8V?
2.3 Should I use FMC interface instead of JXADC?
Thanks you
Jin
wording change
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