Usb serial adapter and groovepi

dogi · September 25, 2014, 11:43am

I am using a USB to TTL Serial Cable - Debug / Console Cable for Raspberry Pi
to power and remote control pi by serial console ($ screen /dev/ttyUSB0 115200), since I enhanced my raspberrypi build with grovepi software stack the console is not showing up anymore (no output at all) … at least rpi is still powering up

Wonder if there is a way to fix for this issue.

JohnC · September 26, 2014, 1:06pm

dogi, you need to re-enable the serial console I think. We haven’t used this particular part, but I think it uses ttl over the pins our firmware reserves for serial communication with the GrovePi.

Here’s an article about setting up TTL:
http://elinux.org/RPi_Serial_Connection

bigb · October 14, 2014, 3:48pm

Are you saying that the RPI’s serial TX/RX pins are being consumed by the GrovePi? It was my understanding looking at your documentation that you’re only consuming the I2C interface (and SPI for Ardunio firmware update) to communicate between the RPI and the GrovePi.

I’ve restored my cmdline.txt setting yet when it gets to the point of prompting for user login, it hangs.

bigb · October 14, 2014, 6:32pm

Another data point is that when I now remove the GrovePi board, I’m still unable to use my debug serial port connection. Looks like /dev/ttyUSB0 is populating but it is not recognizing keyboard input.

bigb · October 15, 2014, 5:32am

Give a man a fish…

Was able to get my serial debug tty working again. Looked through the install.sh script and saw that it was effectively disabled in the /etc/inittab file. So after repairing these two conditions, I was able to boot up and communicate via the debug serial connection with and without the GrovePi attached:

echo " - in /etc/inittab comments out lines containing AMA0"
echo " - in /boot/cmdline.txt removes: console=ttyAMA0,115200 kgdboc=ttyAMA0,115200 console=tty1"

mcauser · October 15, 2014, 5:42am

I added some comments to the install.sh to make it a bit more clear what is going on. Looks like it may have helped

bigb · October 15, 2014, 6:28am

Appreciate it.

Obviously the debug serial was disabled for a purpose so what might that be? In other words what am I going to run up against if I continue to run my system this way?

Also, is there a published API for the I2C interface with the GrovePi Arduino firmware?

mcauser · October 15, 2014, 7:06am

Not sure. Perhaps Karan might be able to shed more light.

I am not really sure what you mean about the API for I2C.

The GrovePi board is basically a custom Arduino (Atmega328p) which exposes digital + analog pins as Grove 4 pin sockets, draws power from the GPIO and is reprogrammable over SPI. The I2C ports are pass-through. Scripts running on the pi can interact with I2C sensors directly as well as predefined commands in the GrovePi firmware, which makes it act sort of like a proxy for the sibling I2C sensors. You issue commands to the GrovePi over the I2C bus and it returns readings from it’s digital, analog, serial or uart ports, or it relays I2C commands to adjacent sensors and returns their response.

If you want to issue your own hand crafted commands to the GrovePi, you basically need to write i2c blocks in the format [GrovePi-i2c-address,command,pin,value1,value2]

The GrovePi listens on the wire for 4 ints then tries to execute the command on the specified pin (and adjacent pin if the sensor uses all 4x wires: DATA,CLOCK,VCC,GND or TX,RX,VCC,GND etc). Some commands use a single value, some use both values, some don’t need any values.

Some of the commands return values - you’ll receive ints back down the wire. Some commands return more ints than others.

The GrovePi Arduino firmware:

github.com

DexterInd/GrovePi/blob/master/Firmware/Source/v1.1/grove_pi_v1_1/grove_pi_v1_1.ino

*/
## License

The MIT License (MIT)

GrovePi for the Raspberry Pi: an open source platform for connecting Grove Sensors to the Raspberry Pi.
Copyright (C) 2017  Dexter Industries

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in
all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,

This file has been truncated. show original

More about the GrovePi protocol:
http://www.dexterindustries.com/GrovePi/engineering/grovepi-protocol-adding-custom-sensors/

bigb · October 15, 2014, 7:42am

Thanks again mcauser.

By API I was meaning the actual data structure to be passed across I2C interface to perform specific operations (e.g., digital read, analog write, etc.). While waiting for a response, I found the version 1.1 sketch being run in the 328p and can see the command breakout. In general, the sketch is actually quite simple. The bit about the I2C ports being passthru is a good tidbit. I’ve yet to dink with I2C so that is good to know.

Also, looking at the port layout I see a port labeled RPISER with a description as a passthru from the RPI. So I would interpret that as being the reason the tty was taken out of the loop with the intent being that the RPI can directly control a serial interface sensor via TX/RX on the GPIO.

karan · October 15, 2014, 7:55am

Hi guys,
Sorry for the confusion with the usage of the Serial debug menu being disabled by default.

The reason that was done is because that the “RPISER” port is connected directly to the Raspberry Pi Serial pins, so that you can attach complex Serial Sensors like the Grove GPS and directly read and write values from the Raspberry Pi.

The GrovePi itself does not use Serial in any way and relies on I2C for communicating with the Raspberry Pi. So if you won’t be using Serial sensors, then you can enable the debug on Serial port without any conflicts.

Thanks,
Karan

dogi · May 11, 2015, 10:41pm

thanks
to make it work I modified the install script this way:

git clone https://github.com/DexterInd/GrovePi.git
cd GrovePi/Script/
chmod +x install.sh
touch /boot/cmdline.txt.bak
touch /etc/inittab.bak
./install.sh