55 lines
1.3 KiB
Plaintext
55 lines
1.3 KiB
Plaintext
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* ICP DAS LP-8841 SPI Controller for RTC
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ICP DAS LP-8841 contains a DS-1302 RTC. RTC is connected to an IO
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memory register, which acts as an SPI master device.
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The device uses the standard MicroWire half-duplex transfer timing.
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Master output is set on low clock and sensed by the RTC on the rising
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edge. Master input is set by the RTC on the trailing edge and is sensed
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by the master on low clock.
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Required properties:
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- #address-cells: should be 1
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- #size-cells: should be 0
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- compatible: should be "icpdas,lp8841-spi-rtc"
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- reg: should provide IO memory address
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Requirements to SPI slave nodes:
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- There can be only one slave device.
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- The spi slave node should claim the following flags which are
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required by the spi controller.
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- spi-3wire: The master itself has only 3 wire. It cannor work in
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full duplex mode.
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- spi-cs-high: DS-1302 has active high chip select line. The master
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doesn't support active low.
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- spi-lsb-first: DS-1302 requires least significant bit first
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transfers. The master only support this type of bit ordering.
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Example:
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spi@901c {
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#address-cells = <1>;
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#size-cells = <0>;
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compatible = "icpdas,lp8841-spi-rtc";
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reg = <0x901c 0x1>;
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rtc@0 {
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compatible = "maxim,ds1302";
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reg = <0>;
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spi-max-frequency = <500000>;
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spi-3wire;
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spi-lsb-first;
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spi-cs-high;
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};
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};
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