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`LTV-1200 --RS232-> Raspberry Pi Serialport --> Local Node.JS Bridge --WebSocket-> Browser Display`
Data streams 'realtime' packets from the LTV at ~ 10ms intervals (+ / - 5ms) (per the datasheet), but I observed some occasional drop-outs: I think these happen when the vent sends some other packet type (alarms).
Otherwise, data is cached locally on the raspberry pi, and clients can request it in intervals: sending with their query the time-stamp of their most-recent slice: the pi should respond as best it can with a full update since then.
Qualitative MVP video below, next steps probably:
- pretty-ify,
- run for ~ hours, verify no memory leaks etc
- do on RPI4, see if HZ can improve
- circuit for RS232 interface, RPI screen mount
- UI for system reset / reboot,
- UI for system state (vent connection OK? ws connection OK?)
- label flows
## Log
## 2020 11 18
In order of appearance, this video should be:
- 'prox pressure'
- 'xdcr flow'
- volume
## 2020 11 05
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### Yonder Phy
We have an RJ45 port, pinouts are
| pin | sig |
| --- | --- |
| 1 | SGND |
| 2 | TxD |
| 3 | RxD |
| 4 | CTS |
| 5 | RTS |
| 6 | SGND |
Seems like this should be straightforward - datasheet notes that data is uni-directional, my guess is that it just spews data out of the port, wouldn't that be nice.
First move is to get it venting. [Setup Guide](https://bu.digication.com/bumc-ed1/ltv-ventilator-setup-and-initial-settings)
OK, have woken it up with a glove, can confirm it has an RS232 out that just spews data - that's great. I do need an RS232 interface though, which swings -10 to +10v here.
### RPI
pi
vent
- do rpi basic setup:
- use mouse, keyboard, hdmi...
- connect to internet, do updates
- install node.js
- `$ curl -sL https://deb.nodesource.com/setup_14.x | sudo -E bash -`
- `$ sudo apt install -y nodejs`
- install raspi-serial
- have to do some serialport config stuff
- might be some trix in here: the bluetooth module uses the serialport, so we have to wrestle for control
- get vscode ?
I think we want RPI4 for this, they have decent UART support now.
- https://learn.pi-supply.com/make/raspberry-pi-4-pinout/
- https://datasheets.raspberrypi.org/bcm2711/bcm2711-peripherals.pdf
OK, turned the vent on today, and got characters from the RS232 port. Have an RPI setup and ready to test with some code tomorrow morning, and a temporary RS232-TTL adapter to splice in between. Some concern about the RPI's serial port being 'in use' when bluetooth module is being used, etc. RPI 4 has mucho ++ serial ports, will try to use one of those in the end run.
So, first move tomorrow is getting the serial port hooked up & seeing if I can pull anything into JS, then is a little software architecting.
## 2020 11 06
Serial on the RPI3 is a pain, have to disable a bunch of things:
https://openenergymonitor.org/forum-archive/node/12311.html
OK, so I:
- used node serialport (not the particular raspi-serial library)
- set it up for /dev/ttyAMA0, the default port
- baudrate to 60096
- use a bytelength parser
- disable the uart terminal / enable the uart hardware in `sudo raspi-config`
- put `dtoverlay=pi3-disable-bt` in `/boot/config.txt`
- did `sudo systemctl disable hciuart`
- rebooted
- now I am recieving bytes
So I should decode some packets.
Packets: decoded. Now I want the 'other end' of it, my bootstrap code / server / client.
Cool, have a bootstrap up, just need to plug it into the ltv, get three plots up and one state-swapping thing, then it should be ahn MVP, next step would be a circuit / display.
OK, I have the client / server architecture setup now... so just one more day at that and I should have an MVP, good enough to proceed with a circuit etc.