The RPi-Basic Spring adapter allows for easy connectivity between a Raspberry PI and any of the LooUQ Circuit River Stream devices, including our LTEm1 Stream modem. The adapter has a voltage regulator to supply the modem with power derived from the Raspberry PI's 5-volt supply and signal connectivity. For applications where the USB port is utilized (Linux) as the communications path between the R-PI and the modem, the IRQ and SPI-CS traces can be easily cut to prevent unexpected interactions.
The RPi-Basic form-factor matching for the Raspberry PI Foundation HAT specification, but since we have not implemented the GPIO automatic mapping we don't call it a HAT. It is available with either stacking or non-stacking 40-pin I/O header (2nd photo, with LTEm1 attached, shows stacking header).
| Signal Name | Physical Pin | Alias | R-PI Type |
|---|---|---|---|
| SPI-CS | 24 | SPI0/CS0 (GPIO8) | Output |
| SPI-MISO | 21 | SPI0 (GPIO9) | Input |
| SPI-MOSI | 19 | SPI0 (GPIO10) | Output |
| SPI-CLK | 23 | SPI0 (GPIO11) | Output |
| IRQ | 15 | GPIO22 | Input |
| PwrKey | 18 | GPIO24 | Output |
| Status | 33 | GPIO13 | Input |
| Reset | 31 | GPIO6 | Output |
| Wake | 29 | GPIO5 | Output |
| Connected | 32 | GPIO12 | Input |
| NewEvent | 37 | GPIO26 | Input |
LooUQ Circuit River Springs are open-hardware and all supporting software/drivers are licensed as open-source. Please visit our GitHub to see our Eagle-CAD design files and our collection of open-source software repositories.
If your application uses the USB interface to the LTEm1 for communications, you will also need to implement 3 GPIO signals to power-on and manage the LTEm1 modem. These are PwrKey, Reset and Status. Status (R-PI input): Indicates that the modem is powered on and ready for command processing. Reset (R-PI output): Forces LTEm1 to initialize. This pin must be setup as R-PI output and set to Low logic level for the LTEm1 to power on. PwrKey (R-PI output): Pulse this pin High (low-high-low) for at least 500 mSec to turn the LTEm1 on, pulse for at least 800 mSec to the the LTEm1 off.