Could somebody tell me please if I connected everything in a right way? I try to connect DHT to my raspberry pi 2. If I try to read data I'm getting:
Data (0): 0x0 0x0 0x0 0x0 0x0
I tried almost every port GPIO
I did everything as it is here:
http://docs.gadgetkeeper.com/pages/viewpage.action?pageId=7700673
It's a little hard to see but that doesn't look like a 10k or 4.7k resistor but like 1k (5 band, Brown, Black, Grey, Brown?).
Edit: As you used a 10 ohm resistor you shorted data to VCC which messes the data transmission up. The DHT11 is fine, you just need to use the proper transistor. You need a so called pull up resistor, which should be like stated around 4-10k.
Related
I'm implementing a virtual instrument on STM32 (STM32F103x). Like a normal "hello world", I tried to start with the simplest MIDI message, sending NOTE-ON MIDI message in a loop to see if it works.
I send MIDI NOTE-ON message for every 500ms, only NOTE-ON message in a forever loop, but it not works. Is there any other MIDI message must be sent to make MIDI works? Like some initialize message?
Based on MIDI 1.0 spec, I finish my code on STM32 by sending MIDI message via USART interface.
Then use a logical analyzer, I confirmed my MIDI message is fully match the MIDI 1.0 spec. At least I believe it correct, no issue. 31250 baud rate, 1 start bit, 1 stop bit, one status message 0x92 followed by two data bytes 0x48 and 0x7F, LSB first.
Below is the NOTE-ON message captured by the logical analyzer on TX line of URAT interface. I continue send the same 3 bytes for every 500ms.
The totally time for those 3 bytes are 960 microseconds also match MIDI 1.0 spec mentioned value.
Then, based on "(CA-033) MIDI 1.0 Electrical Specification Update [2014]", I buy one 5 PIN MIDI OUT jack, connect the URAT TX line to PIN-5 through a 10 Ohm resister, connect 3.3V power to Pin-4 through a 33 Ohm resister, PIN-2 and Jack shield connect to GND. Other optional parts (buffer for Rc, ferrite beads) are not used.
However, when I use a USB-MIDI wire connect my MIDI OUT jack to my PC, nothing happen. The USB-MIDI wire has two LED indicators , one for power another for MIDI signal. After connect, the power LED is light, but the MIDI signal LED never light.
I tried to use logical analyzer to analysis PIN-5 of my MIDI OUT jack, the MIDI message byte are totally same with URAT TX line, and every 500ms one NOTE-ON message. However, it never works.
I also tried to create my own PCB with Dream SAM2695 by follow the SAM2695 Evaluation Boards. Then connect the URAT TX directly to MIDI_IN pin of SAM2695, it still no response. Since I have no confidence on my manual soldering PCB, not sure if the PCB itself has issue cause it no response. So I buy a USB-MIDI wire, but the result as I mentioned above, still no response.
======= Apr.26.2021 Update =========
Based on comments, have tried to check the output of the optocoupler.
Before do this check, I bought several BSS138 to transform the MIDI signal to 5V single use below circuit (of course change the resisters near MIDI JACK pin to 220 Ohm as the spec)
After this change I measured voltage of the 5V URAT TX, it show as 4.8+ V, and Logical Analyzer show correct MIDI note on message of this new 5V MIDI signal. However, it still not works.
The only left troubleshooting method for me is measure the output of the optocoupler on this USB-MIDI wire. But I didn't find an optocoupler on this MIDI USB wire PCB. There even do not have any one component has 4 pins on the PCB (based on my understanding, an optocoupler need at least 4 pins).
There only have one main chip on the PCB, it is possible that the optocoupler is embedded in that chip? Since the pin are too small I failed to connect my logical analyzer to those pin to check.
I really wanted at first an rs232 8-channel relay board that I could command devices to turn on/off with a command string.
All of the ones I found online have the same deficiency in functionality for me: you can't set a subset of relays at the exact time. I can set relay 1 on, and then relay 7 on afterwards, I can set all 8 relays at once, but there is no command structure to pick out the exact leds I would like to turn on/off.
In the past I have dealt with hardware that had a bit-map of the IO pins, and a bit-map of the states and would apply all 8 settings at once. here are some examples:
to set pins 1 and 7 to on and the other pins off (8-bit binary bit-mapping,) send the following byte: in binary: 0100 0001b
to set pins 1,2,3,6 to on and the other pins off (8-bit binary bit-mapping,) send the following byte: in binary: 0010 0111b
I couldn't find any such device to do this so I thought I could make one with a raspberry pi using a simple 8-channel relay board, something like this:
https://www.amazon.com/SainSmart-101-70-102-8-Channel-Relay-Module/dp/B0057OC5WK
but on a Raspberry Pi, I'm running into the same issue: I don't see a way to set the gpio pins as a block command, only individually setting them in a for loop. I looked all morning and can see things like gpioctl, and mmio, but I can't put it all together to a simple proof of concept program on a testboard, any help would be appreciated.
I would really like a solution in C or scripting,
Thanks,
jleslie
Let's say I am talking to a PHY chip via RGMII.
What is the relationship between the serial information transmitted on the RGMII to the signals that go out to the MDI?
I understood from the timing diagram of RGMII that the rising edge is 4 bits and the falling edge is 4 bits. So for each clock that gives 8 bits.
For 100Mbps, the clock required is 25MHz. So for every 25MHz clock cycle, 8 bits are transmitted.
Does the PHY chip simply send each 8 bits over the MDI immediately?
If that is the case, then how do I correctly package these serial 8 bits of data into a proper ethernet frame?
I a trying to troubleshoot a piece of hardware where the PHY does not work properly but the only way troubleshoot is if I can control the RGMII. However, I do not understand this relationship between the RGMII and how it affects the MDI.
I presume that if I look at wireshark, it will not show any packets of information unless I send a string of serialized data in a proper Ethernet frame.
The PHY should have some documentation and sample code. Without, finding out how exactly it works can be a very tedious task.
You can find the general RGMII description here: https://web.archive.org/web/20160303212629/http://www.hp.com/rnd/pdfs/RGMIIv1_3.pdf
I've got a Raspberry Pi Zero W v1.1 set up today and I've been trying GPIO's. Got them (I'll refer to GPIO #3) to output between 3.3v to 0.05v on command using echo 0 > /sys/class/gpio/gpio3/value with direction OUT and got them to read in logic 1 to 0 by connecting pin #7 (GPIO #3) to a ground (will replace with a sensor later on) with direction IN.
My question is: Would you consider this normal that the Raspberry Pi defaults to logic 1 as soon as you enable the export? echo 3 > /sys/class/gpio/export
Can somebody elaborate on why this is? Also, why is this exactly the opposite of this guy's scenario: Reading a sysfs GPIO input pin (direction as "in") always print a fixed value (0)
Kthx
You said there is nothing connected to the pin, yet you read value=1. This is due to internal bias on the input which is weak and can be over-driven by an external circuit if you were to connect something to the pin. The internal bias simply is a large (~1M ohm) resistor to the VCC, so you are reading this bias. Try connecting a 1K ohm resistor from the pin to ground and read it again. It should read value=0 as you were initially expecting.
I try to read a memory cell from a chip with my stm32f103 uC. I send three bytes, one instruction then 2 address bytes. Watching this on a scope I get the MOSI signals back, not the same level, but attenuated. Is that normal? If something's wrong with my chip, should the MOSI signal reflect back on the MISO pin?
You need to send more than 3 bytes master generates the clock. To read something master needs to send dummy bytes.