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by tlfong01
Thu Mar 14, 2019 4:50 am
Forum: Automation, sensing and robotics
Topic: Choosing motors
Replies: 36
Views: 9362

Re: Choosing motors

... reads the MPU6050's register 0x75. The program is fully listed below. tlfong01's MPU6050 Programming Penzu Diary https://penzu.com/p/bcc27149 / ... linux 4.14.34-v7+ arm python3.5.3 # *** Description *** # 1. Setup I2C channel # 2. Reset MPU # 3. Wakeup MPU # 4. Read and print register default ...
by tlfong01
Wed Mar 13, 2019 12:18 pm
Forum: Automation, sensing and robotics
Topic: Choosing motors
Replies: 36
Views: 9362

Re: Choosing motors

... V4.2 - InvenSense 2013 https://www.invensense.com/wp-content/uploads/2015/02/MPU-6000-Register-Map1.pdf Washington University CSE 466 Lab 4: I2C Gyroscope control (Using Teensy) https://courses.cs.washington.edu/courses/cse466/14au/labs/l4/l4.html An Efficient Orientation Filter For Inertial ...
by tlfong01
Mon Mar 11, 2019 2:58 pm
Forum: Automation, sensing and robotics
Topic: Choosing motors
Replies: 36
Views: 9362

Re: Choosing motors

TT RS130 Motor Toy Car tlfong01's Toy Car DIY PenZu Diary https://penzu.com/p/39061ac7 Toy 4WD Assembly and ... can even access external magnetometers or other sensors through an auxiliary master I2C bus, allowing the devices to gather a full set of sensor data without intervention ...
by tlfong01
Mon Mar 11, 2019 7:15 am
Forum: HATs and other add-ons
Topic: I2C I/O PORT EXPANDER QUESTION
Replies: 37
Views: 7444

Re: I2C I/O PORT EXPANDER QUESTION

the EL817C optoisolater current limiting resistance value of 1k is designed to be 5V TTL compatible. You can change it to 6k, so that it is < 1V on and > 2.5V off, in other words, now both Rpi 3V3 and TTL 5V compatible. Getting around Rpi 3V GPIO signal not high enough to switch off EL817C opto iso...
by tlfong01
Sun Mar 10, 2019 12:28 pm
Forum: HATs and other add-ons
Topic: I2C I/O PORT EXPANDER QUESTION
Replies: 37
Views: 7444

Re: I2C I/O PORT EXPANDER QUESTION

tlfong01 wrote: ↑
Sun Mar 10, 2019 1:53 am

Duplicated post by mistake. My apologies.
by tlfong01
Sun Mar 10, 2019 7:09 am
Forum: HATs and other add-ons
Topic: I2C I/O PORT EXPANDER QUESTION
Replies: 37
Views: 7444

Re: I2C I/O PORT EXPANDER QUESTION

(2) Rpi GPIO is only 3V logic. You might need to consider using logical level shifter to convert the signals to 5V. Rpi 3V GPIO Compatible Opto Isolator/Level Converter and Power MOSFET Switch Actually you don't need all things 5V TTL compatible. For example the EL817C optoisolater current limiting...
by tlfong01
Sat Mar 09, 2019 11:12 am
Forum: HATs and other add-ons
Topic: I2C I/O PORT EXPANDER QUESTION
Replies: 37
Views: 7444

Re: I2C I/O PORT EXPANDER QUESTION

tlfong01 wrote: ↑
Sat Mar 09, 2019 8:09 am

EL817C youtube

https://youtu.be/EC-zXCJIfp4 (youtube)
...
by tlfong01
Sat Mar 09, 2019 8:09 am
Forum: HATs and other add-ons
Topic: I2C I/O PORT EXPANDER QUESTION
Replies: 37
Views: 7444

Re: I2C I/O PORT EXPANDER QUESTION

tlfong01 wrote: ↑
Sat Mar 09, 2019 4:00 am

EL817C Assembly and Testing Notes

...
by tlfong01
Sat Mar 09, 2019 4:00 am
Forum: HATs and other add-ons
Topic: I2C I/O PORT EXPANDER QUESTION
Replies: 37
Views: 7444

Re: I2C I/O PORT EXPANDER QUESTION

EL817C Current Limiting Resistor Calculation Notes My lazy hobbyist quick and dirty calculation is summarized below. The current limiting resistor value of 1k should be OK . Update 2019mar11hkt1523 I used an adjustable voltage regulator as a signal source to verify that EL817C is off when signal is...
by tlfong01
Fri Mar 08, 2019 12:56 pm
Forum: HATs and other add-ons
Topic: I2C I/O PORT EXPANDER QUESTION
Replies: 37
Views: 7444

Re: I2C I/O PORT EXPANDER QUESTION

tlfong01 wrote: ↑
Fri Mar 08, 2019 8:59 am
 NE555 > ULN2803 > Songle 5V Relay > DC12V Motor Tested OK


NE555 > ULN2803 > Songle 5V Relay > DC12V Motor Schematic
...
by tlfong01
Fri Mar 08, 2019 9:35 am
Forum: HATs and other add-ons
Topic: I2C I/O PORT EXPANDER QUESTION
Replies: 37
Views: 7444

Re: I2C I/O PORT EXPANDER QUESTION

How much time would you spend on your I2C I/O PORT Expander Project Your project of using Rpi to drive 260 devices using an IO expander is a very complex project, for sure not for the faint of heart newbies. I already have 5 years hobbyist ...
by tlfong01
Fri Mar 08, 2019 8:59 am
Forum: HATs and other add-ons
Topic: I2C I/O PORT EXPANDER QUESTION
Replies: 37
Views: 7444

Re: I2C I/O PORT EXPANDER QUESTION

tlfong01 wrote: ↑
Fri Mar 08, 2019 8:02 am

NE555 drives ULN2803, which drives Songle 5V Relay - Tested OK

https://youtu.be/KpE9n6SSraU (youtube)
...
by tlfong01
Fri Mar 08, 2019 8:02 am
Forum: HATs and other add-ons
Topic: I2C I/O PORT EXPANDER QUESTION
Replies: 37
Views: 7444

Re: I2C I/O PORT EXPANDER QUESTION

tlfong01 wrote: ↑
Fri Mar 08, 2019 6:35 am

ULN2803A Datasheet Summary

Now I am reading the datasheet and making a summary.
...
by tlfong01
Fri Mar 08, 2019 6:35 am
Forum: HATs and other add-ons
Topic: I2C I/O PORT EXPANDER QUESTION
Replies: 37
Views: 7444

Re: I2C I/O PORT EXPANDER QUESTION

tlfong01 wrote: ↑
Fri Mar 08, 2019 4:56 am
 I am using TK73-424 Quad Songle relay which is cheaper than Omron.


TK73-424 Songle Relay Inductance Measurement Resutls

I measured the inductance of the 4 Songle relays, and found them almost identical, about 40mH.
...
by tlfong01
Fri Mar 08, 2019 4:56 am
Forum: HATs and other add-ons
Topic: I2C I/O PORT EXPANDER QUESTION
Replies: 37
Views: 7444

Re: I2C I/O PORT EXPANDER QUESTION

tlfong01 wrote: ↑
Thu Mar 07, 2019 2:55 pm

How deep is your pocket?

Another usual user requirement is "As cheap as possible". I am a poor hobbyist, so I also have this requirement. I am using TK73-424 Quad Songle relay which is cheaper than Omron.
...
by tlfong01
Thu Mar 07, 2019 7:57 am
Forum: HATs and other add-ons
Topic: I2C I/O PORT EXPANDER QUESTION
Replies: 37
Views: 7444

Re: I2C I/O PORT EXPANDER QUESTION

(1) PCA9865 is only TTL 25mA output only, not strong enough to control a 5V relay which needs 70mA. You may need stronger switches such as ULN2803. (2) Rpi GPIO is only 3V logic. You might need to consider using logical level shifter to convert the signals to 5V. MCP23017 + ULN2803 Relay Circuit [/...
by tlfong01
Tue Mar 05, 2019 1:29 am
Forum: HATs and other add-ons
Topic: I2C I/O PORT EXPANDER QUESTION
Replies: 37
Views: 7444

Re: I2C I/O PORT EXPANDER QUESTION

... devices. Similarly, I almost NEVER use Rpi's GPIO pins. I only use the I2C, SPI, and UART pins. This way I can easily port my python/microPython ... my old post on MCP23017 Demuxing . RE: RPI ZERO W MULTIPLE SENSORS - tlfong01 2019-Feb-13 https://www.raspberrypi.org/forums/viewtopic.php?f=91&t=233311#p1429189 ...
by tlfong01
Thu Feb 14, 2019 1:00 pm
Forum: Beginners
Topic: RPI Zero W multiple sensors
Replies: 27
Views: 8280

Re: RPI Zero W multiple sensors

... OK. Then I found MCP3208 and found it better. However, the things I learnt in MCP3008 sadly cannot be transferred to MCP3208. Now I am thinking of I2C ADS1015. The main reason is that it is I2C. ADS101x Ultra-Small, Low-Power, I2C-Compatible, 3.3-kSPS, 12-Bit ADCs With Internal Reference, Oscillator, ...
by tlfong01
Thu Feb 14, 2019 7:08 am
Forum: Beginners
Topic: Resistors and MOSFETs and fire-prevention, oh my
Replies: 156
Views: 19816

Re: Resistors and MOSFETs and fire-prevention, oh my

... Polonium tea! :mrgreen:) Appendix - Rpi3B+ GPIO Voh/Vol no spec and I2C flat rate 100kHz no setting problem RE: DOCUMENTATION BUGS: RPI2&3 ... specs. [/color] RE: RASPBERRY PI3 I2C BAUD RATE SETTING Postby tlfong01 » 2018-Aug-04 Sat 4:33 pm https://www.raspberrypi.org/forums/viewtopic.php?f=29&t=219675&p=1348886&hilit=i2c+100k+hz#p1348886 ...
by tlfong01
Wed Feb 13, 2019 6:51 am
Forum: Beginners
Topic: RPI Zero W multiple sensors
Replies: 27
Views: 8280

Re: RPI Zero W multiple sensors

... Moisture sensor, MCP3008/ADS1115 Tutorial The video below is good because it shows how to use water sensor, SPI MCP3008 and I2C ADS1115. Raspberry Pi Analog Water Sensors ADC Tutorial (mcp3008, ADS1115, level shifter) - 2016oct11 201635,815 views https://www.youtube.com/watch?time_continue=2&v=wJgyszOSoQU ...
by MMoazam
Tue Feb 12, 2019 5:36 pm
Forum: Beginners
Topic: RPI Zero W multiple sensors
Replies: 27
Views: 8280

Re: RPI Zero W multiple sensors

... already know Arduino very well, and the schedule is tight, then it might be better to start with Arduino, use system independent devices such as I2C or SPI, and avoid GPIO, which is not that transferable to Rpi. In my previous projects using Arudino, PyBoard, MicroBit, I almost never use GPIOs ...
by tlfong01
Tue Feb 12, 2019 1:53 pm
Forum: Beginners
Topic: RPI Zero W multiple sensors
Replies: 27
Views: 8280

Re: RPI Zero W multiple sensors

... OK. Then I found MCP3208 and found it better. However, the things I learnt in MCP3008 sadly cannot be transferred to MCP3208. Now I am thinking of I2C ADS1015. The main reason is that it is I2C. I am googling some references, and listed below, in case you are interested to know more about ADC. ...
by tlfong01
Tue Feb 12, 2019 11:39 am
Forum: Beginners
Topic: RPI Zero W multiple sensors
Replies: 27
Views: 8280

Re: RPI Zero W multiple sensors

... already know Arduino very well, and the schedule is tight, then it might be better to start with Arduino, use system independent devices such as I2C or SPI, and avoid GPIO, which is not that transferable to Rpi. In my previous projects using Arudino, PyBoard, MicroBit, I almost never use GPIOs ...
by tlfong01
Wed Jan 30, 2019 9:06 am
Forum: Other
Topic: Raspberry Pi + relay GPIO dont work
Replies: 27
Views: 17870

Re: Raspberry Pi + relay GPIO dont work

@tlfong01 Any advise on : But meanwhile, I would like to explore the : 2. Shift up the Rpi ... with TSX0102 and TXS0104 and found them more or less OK. Now I wish to scale up my I2C devices to more than 128. So I need to consider a 1 to 8 demultiplexing level converter. ...
by tlfong01
Mon Jan 28, 2019 4:45 am
Forum: Automation, sensing and robotics
Topic: MCP23017 Learning Notes
Replies: 34
Views: 4586

Re: Cat Home DIY Q&A - Solenoid MCP23017 How To

I am building on the old ping i2c devices program. So the first step is to check out if the program can still ping M017 OK. RPi GPIO Pin 11 toggling KY019 Program Notes The ping M017 program still working. Before testing M017 toggle, I ...

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