Jan 1, 2017 #1 H HOSSEINGHODS Newbie level 3 Joined Sep 27, 2016 Messages 4 Helped 1 Reputation 2 Reaction score 1 Trophy points 3 Activity points 28 Hi Following sentences are some parts of a datasheet, please take a look at them and tell the difference between the marked terms. In SMII/SS-SMII, TXD1 is not used and should be tied either high or low. In SMII/SS-SMII, RXD1is not used and they are driven low. RMII mode;no switch controller is connected; and TX_EN[7:0] is pulled down. 'Pd' stand for internal pull down (75K ohm) Thanks in advance.
Hi Following sentences are some parts of a datasheet, please take a look at them and tell the difference between the marked terms. In SMII/SS-SMII, TXD1 is not used and should be tied either high or low. In SMII/SS-SMII, RXD1is not used and they are driven low. RMII mode;no switch controller is connected; and TX_EN[7:0] is pulled down. 'Pd' stand for internal pull down (75K ohm) Thanks in advance.
Jan 1, 2017 #2 M mjuneja Advanced Member level 4 Joined Aug 28, 2016 Messages 105 Helped 12 Reputation 24 Reaction score 10 Trophy points 18 Location Bangalore, India Activity points 674 HOSSEINGHODS said: Hi Following sentences are some parts of a datasheet, please take a look at them and tell the difference between the marked terms. In SMII/SS-SMII, TXD1 is not used and should be tied either high or low. In SMII/SS-SMII, RXD1is not used and they are driven low. RMII mode;no switch controller is connected; and TX_EN[7:0] is pulled down. 'Pd' stand for internal pull down (75K ohm) Thanks in advance. Click to expand... Tied high means connected to Vcc using some current limiting resistor. Tied low/driven low/pulled down/internal pull down means connected to gnd again using current limiting resistor.
HOSSEINGHODS said: Hi Following sentences are some parts of a datasheet, please take a look at them and tell the difference between the marked terms. In SMII/SS-SMII, TXD1 is not used and should be tied either high or low. In SMII/SS-SMII, RXD1is not used and they are driven low. RMII mode;no switch controller is connected; and TX_EN[7:0] is pulled down. 'Pd' stand for internal pull down (75K ohm) Thanks in advance. Click to expand... Tied high means connected to Vcc using some current limiting resistor. Tied low/driven low/pulled down/internal pull down means connected to gnd again using current limiting resistor.
Jan 2, 2017 #3 H HOSSEINGHODS Newbie level 3 Joined Sep 27, 2016 Messages 4 Helped 1 Reputation 2 Reaction score 1 Trophy points 3 Activity points 28 Thanks, some other questions; consider a pin which is internally pulled up (with an internal 75 K ohm resistor), is it necessary to pull this pin up externally? I have seen people doing this! what does keep logic low level mean?
Thanks, some other questions; consider a pin which is internally pulled up (with an internal 75 K ohm resistor), is it necessary to pull this pin up externally? I have seen people doing this! what does keep logic low level mean?
Jan 2, 2017 #4 M mjuneja Advanced Member level 4 Joined Aug 28, 2016 Messages 105 Helped 12 Reputation 24 Reaction score 10 Trophy points 18 Location Bangalore, India Activity points 674 1. I think adding an external pull up resistor will leads to a strong pull up for that particular pin. 2. "keep logic low" --> connecting the specific pin to logic '0' voltage or pulled down.
1. I think adding an external pull up resistor will leads to a strong pull up for that particular pin. 2. "keep logic low" --> connecting the specific pin to logic '0' voltage or pulled down.