Yoking
Newbie level 6
im now encounter a problem with EPM240 high impedance output,it seems like the io port has connected a low value R to the ground that drop down the voltage provided by other signal on the bus.
The circut is very simple.
and the verilog code is:
assign aup=adjlevel?1'b0:1'bz;
assign bdown=adjlevel?1'b1:1'bz;
aup is connecting to the 485 bus a line with a 3.3k resistor.
bdown is connecting to the 485 bus a line with a 3.3k resistor.
my intention is to set aup=1'b0 when adjlevel=1'b1,and aup=1'b1 when adjlevel=1'b0.
but when it is set with aup=1'bz, the EPM240 output pin has change the signal voltage that provided by the 485 bus.(meanning only the output pin,not the 485 a line voltage)
i have try other way by setting the output pin with oc function,but it cant work.
there are no design error in this circuit and it can achieve the desired result
The wave form in TDS1k2k_FP.bmp( 2V/DIV ) are the correct performance,but i cant reach this result.........
please help.........
The circut is very simple.
and the verilog code is:
assign aup=adjlevel?1'b0:1'bz;
assign bdown=adjlevel?1'b1:1'bz;
aup is connecting to the 485 bus a line with a 3.3k resistor.
bdown is connecting to the 485 bus a line with a 3.3k resistor.
my intention is to set aup=1'b0 when adjlevel=1'b1,and aup=1'b1 when adjlevel=1'b0.
but when it is set with aup=1'bz, the EPM240 output pin has change the signal voltage that provided by the 485 bus.(meanning only the output pin,not the 485 a line voltage)
i have try other way by setting the output pin with oc function,but it cant work.
there are no design error in this circuit and it can achieve the desired result
The wave form in TDS1k2k_FP.bmp( 2V/DIV ) are the correct performance,but i cant reach this result.........
please help.........
