https://github.com/pstolarz/librasp
Raspberry Pi library for GPIO, 1-Wire, SPI, System Time Counter (STC) access. There have been provided APIs for handling various popular devices.
https://github.com/pstolarz/librasp
dallas-family dht-temperature-sensors dht11 dht22 ds18b20 embedded embedded-systems gpio hc-sr04 i2c library nrf24l01 one-wire piso-shift-register raspberry raspberry-pi-library sensor spi stc temperature-sensor
Last synced: 15 days ago
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Raspberry Pi library for GPIO, 1-Wire, SPI, System Time Counter (STC) access. There have been provided APIs for handling various popular devices.
- Host: GitHub
- URL: https://github.com/pstolarz/librasp
- Owner: pstolarz
- License: bsd-2-clause
- Created: 2015-11-09T13:07:03.000Z (over 9 years ago)
- Default Branch: master
- Last Pushed: 2023-01-24T08:04:13.000Z (over 2 years ago)
- Last Synced: 2025-03-25T23:24:38.836Z (about 1 month ago)
- Topics: dallas-family, dht-temperature-sensors, dht11, dht22, ds18b20, embedded, embedded-systems, gpio, hc-sr04, i2c, library, nrf24l01, one-wire, piso-shift-register, raspberry, raspberry-pi-library, sensor, spi, stc, temperature-sensor
- Language: C
- Homepage:
- Size: 184 KB
- Stars: 21
- Watchers: 5
- Forks: 2
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
- License: LICENSE
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README
librasp
=======
Raspberry Pi library for GPIO, 1-Wire, SPI, System Time Counter (STC) access.
As an example of usage there have been provided APIs for handling various
popular devices like wireless nRF24L01 transceiver, DHT temperature sensors
(DHT11/22), Dallas family of temperature sensors (e.g. DS18B20, DS1822, DS1825),
HC-SR04 distance sensor, PISO shift register...
API specification contained in the library headers (see [`src/inc/librasp`](src/inc/librasp)).
For examples look in [`examples`](examples).
NOTE: 1-wire and SPI API bases on generic Linux interfaces (`ioctl(2)`, `netlink(3)`)
and doesn't relay on any RPi platform specific details. For this reason the
1-wire and SPI services may be used on any embedded Linux platform (e.g.
[`dsth_list`](examples/dsth_list.c) and [`dsth_list2`](examples/dsth_list2.c)
examples may be used to read-out connected Dallas sensors).
Compilation
-----------
make
produces static library `src/librasp.a` which may be linked into an application.
make examples
will compile examples.
There is possible to cross-compile the library by setting `CROSS_COMPILE` (for
the project `Makefile`) to the tool-chain prefix:
CROSS_COMPILE= make
1-wire and parasite powering
----------------------------
The original Linux kernel 1-wire driver (the `wire` module) doesn't provide
proper interface for parasite powering of 1-wire slaves via userland's netlink
protocol.
1. To handle this issue there has been provided a patch for the kernel allowing
the library to fully support the parasite mode. Look in [`src/kernel`](src/kernel)
directory for more info.
2. Configure the library with `CONFIG_WRITE_PULLUP` parameter while building
the library (see [`src/config.h`](src/config.h) header for details).
3. RPi uses `w1-gpio` module as a 1-wire bus master driver. The driver needs
to be configured to support bit-banged strong pull-up on the data wire,
required for parasite powering of the connected slaves. Add the following
line in `/boot/config.txt` to turn it on via the device-tree overlay (reboot
is required):
`dtoverlay=w1-gpio,pullup=on`
NOTE: This step is not required when using [`w1-gpio-cl`](https://github.com/pstolarz/w1-gpio-cl)
driver instead of `w1-gpio`.
To reach for the full power of the library, it is **strongly recommended**
to use the `w1-gpio-cl` driver instead of the standard one. The primary
benefit is support for more than one bus master simultaneously and much
more mature parasite powering handling. See the above link for more
details.
Refer `examples/dsth_list*` samples for details on probing the parasite
powered Dallas family of temperature sensors.
License
-------
2 clause BSD license. See [LICENSE](LICENSE) file for details.