Bi-directional Buffer with Non-inverting CMOS input and gated Pull-down and Pull-up, Strength 4ma @ 3.3V, Normal, High noise
- vsdbbcud4f is a GPIO pin (General purpose input/output)
- The GPIO pin is controlled by the user to get a desired mode of the whole chip
- The input/output mode can be selected by giving the enable pin to logic high or low
- Both the buffers are connected in a bidirectional fashion which allows the data to flow in either of the direction
- pin A is where the input is given
- pin EN is the enable pin which is used to determine the mode of the circuit (input/output)
- pin PI is the input to the PAD cell
- pin PUEN is used to pull-up the input when it is in floating state
- pin PDEN is used to pull-down the input when it is floating state
- pin Y is the output
- pin PO is the output of the PAD cell
according to https://www.vlsisystemdesign.com/ip/
characterstics of inputs and outputs of GPIO circuit are shown in the plot.Inputs:A,EN,PUEN,PDEN,PI
Outputs:Y,PO
when the enable is 0 output Y is same as the input A when enable is 1 output varies according to the truth table in https://www.vlsisystemdesign.com/ip/ for any value of input A
ngspice plots for GPIO LTspice circuit EN,A
and PI,Y,PO
ngspice cmos.sp
CMOS characterstics in NGspice plot
ngspice nand.sp
NAND inputs NGspice plots A and B
NAND output NGspice plot
ngspice tristate.sp
NGspice plots for tristate buffer inputs A and EN
Ngspice plots for tristate buffer output
ngspice gpio.sp
Ngspice plot for PO
post-layout
Ngspice plot for PI and Y
post-layout
Ngspice plot for A and EN
post-layout
ISSUES:
- performance of the pre-layout simulation is limited to milliseconds simulation time should update it to get all the plots in nanoseconds since we are using everything in 180nm technology
- PUEN and PDEN are not included in post layout simulation yet
- Download LTspice from here ltspice_download
- Now click on the download button for windows.
- Now click on the application
ltspice
from your downloads and accept and continue. - The simulator is installed and is ready to use.
- download the
ltspice
zip file from the repository - open the circuit with a file .asc file extension
- goto
view->spice netlsit
and copy the content in there - open a new text file and paste the spice netlsit and add the command lines according to ngspice
- save the text file with a .cir extension
ngspice is the open source simulator. Follow the steps below to install ngspice on windows10:
- Click on this to download ngspice software.
- Click on the download button.
- You are directed to the download page. Then follow the installation steps.
- The software is now donloaded and ready to use.
- open
ngspice->spice64->bin
and save the .cir file in this location also add the model files in the same location - now open ngspice application and type filename.cir to get the corresponding output graphs
- goto
administartion->synaptic package manager->search->magic
- mark it for installation and proceed with the next steps
- once the installation is completed close the synaptic manager
- download the above files from repository and unzip them
- open the terminal in the folder and tpye
magic -T osu180nm.tech filename.mag
for example if we want to open the gpio layout typemagic -T osu180nm.tech gpio.mag
- This opens the layout
- now goto the corresponding tckon dialoge box and type
extract all
which generates a netlist with the extension ext now to convert into spice typeext2spice
- a spice netlsit is generated open it and add the pmos and nmos model files and some lines to run it through ngspice
- save the files with a .sp extension
-
Download the magic.sh file
-
Copy paste the below commands one after another
cd Downloads/
chmod +x magic.sh
./magic.sh
Magic tool will be opened with minimum technology file by default. Follow below steps to open magic with osu180nm tech file.
-
Download the
osu180nm.tech
file from the uploaded files. Copy and paste the entire content inText Editor
and save it asosu180nm.tech
. -
Open the Terminal and copy, paste the commands mentioned below.
sudo cp osu180nm.tech /usr/local/lib/magic/sys/
cd /usr/local/lib/magic/sys/
ls
cd
clear
-
You have successfully added osu180nm.tech file!
-
Just open the terminal and type
magic -T osu180nm.tech filename.mag
to begin layout.
- goto
administration->synaptic package manager->search->ngspice
- mark it for installation and proceed with further steps
- open in terminal->ngspice and check if it is working to come out of ngspice type
exit
in terminal - type
ngspice filename.sp
and check the output graphs
- It's not directly supported, so we need to download
WineHQ
. Wine is a linux software that creates windows environment and allows you to run various windows programs. - Copy paste the commands mentioned below one after the other in the terminal for downloading and installing.
sudo dpkg --add-architecture i386
wget -O - https://dl.winehq.org/wine-builds/winehq.key | sudo apt-key add -
sudo add-apt-repository 'deb https://dl.winehq.org/wine-builds/ubuntu/ focal main'
sudo apt update
sudo apt install --install-recommends winehq-stable
- Download LTSpice.
- Click on
Download for Windows
. - Install it by clicking on
-> next
. - After installing , click on open with
WineHQ windows program loader
.
LTSpice
is now installed and you can design the circuit```
Cloning a github repository creates a local copy of a remote repo and this allows us to make any changes to the files locally without affecting the main repository. To clone the IP onto your system copy paste the commands given below.
$ sudo apt install -y git
$ git clone https://github.com/gowthaminalla/vsdbbcud4f.git
$ cd vsdbbcud4f/magic
- Nalla Gowthami, Electronics and instrumentation engineering, NIT Rourkela, gowthaminalla1821@gmail.com
- Kunal Gosh Director, Vsd Corp Pvt.Ltd, kunalpgosh@gmail.com
- Phillip Guhring, Software architect at Libresilicon Association pg@futureware.at
- Dr.Gaurav Trivedi Co-principal investigator, EICT academy, and associative proffessor, EEE depatement, IIT Guwahati, trivedi@iitg.ac.in