Prototype Hardware Configuration
Reference should be made to the attached diagram, which shows what we installed during August and ran with the Resistance Probe connected to sumppi and (unsuccessfully so far), the float switch connected to buttspi.
During operation of the prototype system a continual circulation of the water in the in the Butts and Sump will be maintained by allowing a small quantity of water to flow (by gravity) from the Butts to the Sump.
Software Environment
The Raspbian version is Stretch.
Communications
Communications between sumppi and buttspi shall be via the Ethernet link.
Software Requirements for sumppi
For the current deployment, sumppi has only got one probe connected, a resistance probe based on conductivity. As the water covers various contacts at 100 mm intervals, a small current is detected and turned into a logic voltage. The probe contacts are Active-Low, so the input to the Interfacing Board is 0 V when the probe contact is covered and 5 V when it is dry.
The sumppi shall:
- Monitor the level of the water in the sump frequently by reading the outputs of the Resistance Probe.
- Write the results of the sump level measurements to a local file for future analysis and diagnostic purposes.
- Establish communications between itself and buttspi by sending packets to it and listening for a response.
- Interrogate buttspi frequently to monitor the level of water in the Butts.
- Using the results obtained from the level measurements, operate the butts pump to maintain the level of the water in the sump between <Low Level> mm and <High Level> mm.
- Suspend pumping of water to the Butts if the Float Switch is actuated, signalling that the Butts are full.
- <Low Level> mm and <High Level> mm will be determined during development, but are assumed to be between 300 mm and 700 mm initially.
- If possible, a background pumping level should be maintained, so that under stable conditions the Butts Pump is enabled at regular intervals to keep the sump water level close to <High Level>, but without exceeding it. In other words the average rate of flow of water from the Sump to the Butts should equal the rate of flow from the Butts to the Sump. It is recognised that the flow into the sump will reduce as the level of water in the Butts decreases, so the final algorithm should take this into account.
- When the Butts are full, then no more water will be pumped out of the sump, so the excess will be lost through the overflow into the soakaway.
For the current deployment, buttspi has only got one probe connected, a float switch. As the water reaches the top of the Butts a microswitch is made. The probe is Active-Low, so the input to the Interfacing Board is 0 V when the float switch is closed and 5 V when it is open.
The buttspi shall:
- Monitor the state of the float switch frequently.
- Write the results of the float switch state to a local file for future analysis and diagnostic purposes.
- Establish communications between itself and sumppi by responding on the network to packets from it.
- Send the current state of the float switch to sumppi when requested.