Onewire RMT

Github Repo	C Header	C source	JS source
mongoose-os-libs/onewire-rmt	OnewireRmt.h

Based on https://github.com/nodemcu/nodemcu-firmware/blob/dev-esp32/components/platform/onewire.c

It uses 2 RMT channels, one for RX and one for TX. Create the onewire object like this:

OnewireRmt* mgos_onewire_rmt_create(int pin,int rmt_rx,int rmt_tx);

or

OnewireRmt(uint8_t pin,uint8_t rmt_rx,uint8_t rmt_tx);

---

reset

uint8_t reset(void);

Perform a 1-Wire reset cycle. Returns 1 if a device responds with a presence pulse. Returns 0 if there is no device or the bus is shorted or otherwise held low for more than 250uS

select

void select(const uint8_t rom[8]);

Issues a 1-Wire rom select command, you do the reset first.

skip

void skip(void);

Issues a 1-Wire rom skip command, to address all on bus.

write

void write(uint8_t v, uint8_t power = 0);
    void write_bytes(const uint8_t *buf, uint16_t count, bool power = 0);

Write a byte/sequence of bytes. If 'power' is one then the wire is held high at the end for parasitically powered devices. You are responsible for eventually depowering it by calling depower() or doing another read or write.

read

uint8_t read(void);
    void read_bytes(uint8_t *buf, uint16_t count);

Read a byte/sequence of bytes.

write_bit

void write_bit(uint8_t v);

Write a bit. The bus is always left powered at the end, see note in write() about that.

read_bit

uint8_t read_bit(void);

Read a bit.

depower

void depower(void);

Stop forcing power onto the bus. You only need to do this if you used the 'power' flag to write() or used a write_bit() call and aren't about to do another read or write. You would rather not leave this powered if you don't have to, just in case someone shorts your bus.

reset_search

void reset_search();

Clear the search state so that if will start from the beginning again.

target_search

void target_search(uint8_t family_code);

Setup the search to find the device type 'family_code' on the next call to search(*newAddr) if it is present.

search

uint8_t search(uint8_t *newAddr, bool search_mode = true);

Look for the next device. Returns 1 if a new address has been returned. A zero might mean that the bus is shorted, there are no devices, or you have already retrieved all of them. It might be a good idea to check the CRC to make sure you didn't get garbage. The order is deterministic. You will always get the same devices in the same order.

crc8

static uint8_t crc8(const uint8_t *addr, uint8_t len);

Compute a Dallas Semiconductor 8 bit CRC, these are used in the ROM and scratchpad registers.

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