Merge branch 'nfc-production-ready' into 'master' (a66936fa) · Commits · PoolPay Heidelberg / PoolPay

README.md

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		@@ -54,12 +54,9 @@ Then, connect the cables to the Pi as described in this chart:
		2. Go to “Interface Options”
		3. Go to “SPI”
		4. Enable it (no reboot necessary)

		<details>
		<summary>Further information on enabling SPI</summary>

		Enabling SPI will place the line `dtparam=spi=on` in the file `/boot/firmware/config.txt`
		</details>
		* This will enable the first SPI bus (SPI0)
		5. Add the line `dtoverlay=spi1-1cs,cs0_pin=16` somewhere in `/boot/firmware/config.txt` (reboot might be necessary here)
		* This will enable the second SPI bus (SPI1). Furthermore, it will set the Chip Select pin for device 0 (`cs0`) to GPIO 16.

		<details>
		<summary>Links</summary>
		@@ -69,6 +66,8 @@ Enabling SPI will place the line `dtparam=spi=on` in the file `/boot/firmware/co
		- [Datasheet (de)](https://cdn-reichelt.de/documents/datenblatt/A300/SBC-RFID-RC522_DB.pdf)
		- [Instructions (de)](https://cdn-reichelt.de/documents/datenblatt/C300/SBC-RFID-RC522-ANLEITUNG-08-07-2019.pdf)
		- [Instructions (en)](https://cdn-reichelt.de/documents/datenblatt/C300/SBC-RFID-RC522-MANUAL-08-07-2019.pdf)
		- [How to enable SPI0 and SPI1 at the same time](https://raspberrypi.stackexchange.com/questions/73346/how-to-enable-spi1-and-spi0-at-the-same-time)
		- [SPI pinout map](https://pinout.xyz/pinout/spi)
		</details>

		### WiFi hotspot

docs/musings/gpio.md

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		# GPIO

		We need to use `rpi-lgpio` instead of `rpi-gpio` so that edge detection works.

		See Raspberry Pi book, page 632 and 624.

docs/musings/spi.md

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		## What does enabling SPI do?

		Enabling SPI will place the line `dtparam=spi=on` in the file `/boot/firmware/config.txt`.

		## There are two SPI buses (SPI0 and SPI1), both of which support multiple devices

		Multiple devices can be connected to a single SPI bus (e.g. SPI0). They share the SCLK (clock), MISO and MOSI pins, however, each device has to be wired to a dedicated Chip Select (CS, = CE) pin. This is why an SPI devices is listed as `/dev/spi0.0`: The first `0` is the bus, the second `0` the device.

		So, do we use this to connect both the LCD and the NFC reader? Actually, no.

		The Raspberry Pi also has two SPI buses (SPI0 and SPI1). They have different SCLK, MISO and MOSI pins; and as stated above, each SPI bus has its own set of CS pins. In the pinout.xyz diagram, you can see that there is e.g. a `SPI0 CE0` and a `SPI1 CE0` pin.

		Okay, so we wire up the LCD on SPI0 as device 0 and connect it to the respective pins; and then the NFC reader on SPI1 as device 0 and connect it to the respective pins, right? Almost.

		The problem is that `SPI1 CE0` is pin 18, which is occupied by the GPIO header for the display. I don't know if it is needed, but I didn't want to take the risk. This is why I am remapping pin 18 (which would normally be `SPI1 CE2`) to the Chip Select pin for device 0 on SPI1. This is done with the `cs0_pin=16` instruction.

		This means that the NFC reader will be `/dev/spi1.0` (device 0 on SPI1), but wired physically as if it were device 2.
		No newline at end of file

docs/nfc_wiring_static.png

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docs/wiring/nfc.html

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		@@ -11,40 +11,36 @@
		background: black !important;
		}

		.pin1 .pin {
		.pin31 .pin {
		background: gray !important;
		}

		.pin6 .pin {
		.pin34 .pin {
		background: blue !important;
		}

		.pin6 .pin {
		background: blue !important;
		}

		.pin18 .pin {
		.pin37 .pin {
		background: rgb(165, 118, 42) !important;
		/* brown */
		}

		.pin22 .pin {
		.pin33 .pin {
		background: purple !important;
		}

		.pin24 .pin {
		.pin36 .pin {
		background: red !important;
		}

		.pin19 .pin {
		.pin38 .pin {
		background: yellow !important;
		}

		.pin21 .pin {
		.pin35 .pin {
		background: green !important;
		}

		.pin23 .pin {
		.pin40 .pin {
		background: orange !important;
		}
		</style>
		@@ -76,7 +72,7 @@
		class="phys">9</span> Ground</span><span class="pin"></span></a></li>
		<li class="pin11 gpio"><a href="https://pinout.xyz/pinout/pin11_gpio17"
		title="Wiring Pi pin 0"><span class="default"><span class="phys">11</span> <span
		class="name">GPIO 17</span></span><span class="pin"></span></a></li>
		class="name">GPIO 17</span> <small>(SPI1 CE1)</small></small></span><span class="pin"></span></a></li>
		<li class="pin13 gpio"><a href="https://pinout.xyz/pinout/pin13_gpio27"
		title="Wiring Pi pin 2"><span class="default"><span class="phys">13</span> <span
		class="name">GPIO 27</span></span><span class="pin"></span></a></li>
		@@ -118,7 +114,7 @@
		class="pin"></span></a></li>
		<li class="pin35 gpio pcm"><a href="https://pinout.xyz/pinout/pin35_gpio19"
		title="Wiring Pi pin 24"><span class="default"><span class="phys">35</span> <span
		class="name">GPIO 19</span> <small>(PCM FS)</small></span><span
		class="name">GPIO 19</span> <small>(SPI1 MISO)</small></span><span
		class="pin"></span></a></li>
		<li class="pin37 gpio"><a href="https://pinout.xyz/pinout/pin37_gpio26"
		title="Wiring Pi pin 25"><span class="default"><span class="phys">37</span> <span
		@@ -149,7 +145,7 @@
		class="pin"></span></a></li>
		<li class="pin12 gpio pcm"><a href="https://pinout.xyz/pinout/pin12_gpio18"
		title="Wiring Pi pin 1"><span class="default"><span class="phys">12</span> <span
		class="name">GPIO 18</span> <small>(PCM CLK)</small></span><span
		class="name">GPIO 18</span> <small>(SPI1 CE0)</small></span><span
		class="pin"></span></a></li>
		<li class="pin14 gnd"><a href="https://pinout.xyz/pinout/ground" title="">
		<span class="default"><span class="phys">14</span> Ground</span><span
		@@ -194,14 +190,14 @@
		</li>
		<li class="pin36 gpio"><a href="https://pinout.xyz/pinout/pin36_gpio16"
		title="Wiring Pi pin 27"><span class="default"><span class="phys">36</span> <span
		class="name">GPIO 16</span></span><span class="pin"></span></a></li>
		class="name">GPIO 16</span> <small>(SPI1 <s>CE2</s> CE0, for us)</small></span><span class="pin"></span></a></li>
		<li class="pin38 gpio pcm"><a href="https://pinout.xyz/pinout/pin38_gpio20"
		title="Wiring Pi pin 28"><span class="default"><span class="phys">38</span> <span
		class="name">GPIO 20</span> <small>(PCM DIN)</small></span><span
		class="name">GPIO 20</span> <small>(SPI1 MOSI)</small></span><span
		class="pin"></span></a></li>
		<li class="pin40 gpio pcm"><a href="https://pinout.xyz/pinout/pin40_gpio21"
		title="Wiring Pi pin 29"><span class="default"><span class="phys">40</span> <span
		class="name">GPIO 21</span> <small>(PCM DOUT)</small></span><span
		class="name">GPIO 21</span> <small>(SPI1 SCLK)</small></span><span
		class="pin"></span></a></li>
		</ul>
		</nav>