From 2a4b380cb715fface63a438185502f2a96d58d80 Mon Sep 17 00:00:00 2001 From: Marc <35759328+marcemmers@users.noreply.github.com> Date: Fri, 25 Apr 2025 00:40:32 +0200 Subject: [PATCH] Search can use the normal write/read instructions --- embassy-rp/src/pio_programs/onewire.rs | 129 ++++++++++++------------- 1 file changed, 62 insertions(+), 67 deletions(-) diff --git a/embassy-rp/src/pio_programs/onewire.rs b/embassy-rp/src/pio_programs/onewire.rs index 9f2ed5695..82fd98b96 100644 --- a/embassy-rp/src/pio_programs/onewire.rs +++ b/embassy-rp/src/pio_programs/onewire.rs @@ -12,7 +12,6 @@ pub struct PioOneWireProgram<'a, PIO: Instance> { prg: LoadedProgram<'a, PIO>, reset_addr: u8, next_bit_addr: u8, - search_addr: u8, } impl<'a, PIO: Instance> PioOneWireProgram<'a, PIO> { @@ -53,35 +52,17 @@ impl<'a, PIO: Instance> PioOneWireProgram<'a, PIO> { ; The low pulse was already done, we only need to delay and poll the bit in case we are reading write_1: nop side 0 [( 6 / CLK) - 1] ; Delay before sampling the input pin - in pins, 1 side 0 [(54 / CLK) - 1] ; This writes the state of the pin into the ISR + in pins, 1 side 0 [(48 / CLK) - 1] ; This writes the state of the pin into the ISR ; Fallthrough ; This is the entry point when reading and writing data public next_bit: .wrap_target - out x, 1 side 0 [(18 / CLK) - 1] ; Stalls if no data available in TX FIFO and OSR - jmp x--, write_1 side 1 [(12 / CLK) - 1] ; Do the always low part of a bit, jump to write_1 if we want to write a 1 bit - in null, 1 side 1 [(60 / CLK) - 1] ; Do the remainder of the low part of a 0 bit + out x, 1 side 0 [(12 / CLK) - 1] ; Stalls if no data available in TX FIFO and OSR + jmp x--, write_1 side 1 [( 6 / CLK) - 1] ; Do the always low part of a bit, jump to write_1 if we want to write a 1 bit + in null, 1 side 1 [(54 / CLK) - 1] ; Do the remainder of the low part of a 0 bit ; This writes 0 into the ISR so that the shift count stays in sync .wrap - - public search: - set x, 1 side 0 [(78 / CLK) - 1] ; Set x to 1 for the inner loop - search_inner: - ; Read 2 bits - nop side 1 [(12 / CLK) - 1] ; Do the always low part of a bit - nop side 0 [( 6 / CLK) - 1] ; Delay before sampling the input pin - in pins, 1 side 0 [(54 / CLK) - 1] ; This writes the state of the pin into the ISR - jmp x--, search_inner side 0 [(18 / CLK) - 1] - ; Fallthrough - - ; Write output - out x, 1 side 0 [( 6 / CLK) - 1] ; Stalls if no data available in TX FIFO and OSR - jmp x--, search side 1 [(12 / CLK) - 1] ; Do the always low part of a bit, jump to search to write a 1 bit - ; Fallthrough - - set x, 1 side 1 [(60 / CLK) - 1] ; Set x to 1 for the inner loop, write the remainder of the low part of a 0 bit - jmp search_inner side 0 [(18 / CLK) - 1] "# ); @@ -89,7 +70,6 @@ impl<'a, PIO: Instance> PioOneWireProgram<'a, PIO> { prg: common.load_program(&prg.program), reset_addr: prg.public_defines.reset as u8, next_bit_addr: prg.public_defines.next_bit as u8, - search_addr: prg.public_defines.search as u8, } } } @@ -98,7 +78,6 @@ pub struct PioOneWire<'d, PIO: Instance, const SM: usize> { sm: StateMachine<'d, PIO, SM>, cfg: Config<'d, PIO>, reset_addr: u8, - search_addr: u8, next_bit_addr: u8, } @@ -119,13 +98,16 @@ impl<'d, PIO: Instance, const SM: usize> PioOneWire<'d, PIO, SM> { cfg.use_program(&program.prg, &[&pin]); cfg.set_in_pins(&[&pin]); - let byte_shift = ShiftConfig { + cfg.shift_in = ShiftConfig { + auto_fill: true, + direction: ShiftDirection::Right, + threshold: 8, + }; + cfg.shift_out = ShiftConfig { auto_fill: true, direction: ShiftDirection::Right, threshold: 8, }; - cfg.shift_in = byte_shift; - cfg.shift_out = byte_shift; let divider = (clk_sys_freq() / 1000000) as u16 * 6; cfg.clock_divider = divider.into(); @@ -142,11 +124,11 @@ impl<'d, PIO: Instance, const SM: usize> PioOneWire<'d, PIO, SM> { sm, cfg, reset_addr: program.reset_addr, - search_addr: program.search_addr, next_bit_addr: program.next_bit_addr, } } + /// Perform an initialization sequence, will return true if a presence pulse was detected from a device pub async fn reset(&mut self) -> bool { // The state machine immediately starts running when jumping to this address unsafe { @@ -164,18 +146,18 @@ impl<'d, PIO: Instance, const SM: usize> PioOneWire<'d, PIO, SM> { found } - /// Write bytes over the wire + /// Write bytes to the onewire bus pub async fn write_bytes(&mut self, data: &[u8]) { let (rx, tx) = self.sm.rx_tx(); for b in data { tx.wait_push(*b as u32).await; - // Empty the buffer that is always filled + // Empty the buffer that is being filled with every write let _ = rx.wait_pull().await; } } - /// Read bytes from the wire + /// Read bytes from the onewire bus pub async fn read_bytes(&mut self, data: &mut [u8]) { let (rx, tx) = self.sm.rx_tx(); for b in data { @@ -187,19 +169,29 @@ impl<'d, PIO: Instance, const SM: usize> PioOneWire<'d, PIO, SM> { } async fn search(&mut self, state: &mut PioOneWireSearch) -> Option { - let _ = self.reset().await; - self.write_bytes(&[0xF0]).await; + if !self.reset().await { + // No device present, no use in searching + state.finished = true; + return None; + } + self.write_bytes(&[0xF0]).await; // 0xF0 is the search rom command - let shift_cfg = self.prepare_search(); + self.prepare_search(); let (rx, tx) = self.sm.rx_tx(); - let mut value = 0u64; + let mut value = 0; let mut last_zero = 0; for bit in 0..64 { - let push = match rx.wait_pull().await { - 0b00 => { + // Write 2 dummy bits to read a bit and its complement + tx.wait_push(0x1).await; + tx.wait_push(0x1).await; + let in1 = rx.wait_pull().await; + let in2 = rx.wait_pull().await; + let push = match (in1, in2) { + (0, 0) => { + // If both are 0, it means we have devices with 0 and 1 bits in this position let write_value = if bit < state.last_discrepancy { (state.last_rom & (1 << bit)) != 0 } else { @@ -213,10 +205,11 @@ impl<'d, PIO: Instance, const SM: usize> PioOneWire<'d, PIO, SM> { 0 } } - 0b01 => 0, - 0b10 => 1, + (0, 1) => 0, // Only devices with a 0 bit in this position + (1, 0) => 1, // Only devices with a 1 bit in this position _ => { - self.restore_after_search(&shift_cfg); + // If both are 1, it means there is no device active and there is no point in continuing + self.restore_after_search(); state.finished = true; return None; } @@ -226,9 +219,10 @@ impl<'d, PIO: Instance, const SM: usize> PioOneWire<'d, PIO, SM> { value |= 1 << 63; } tx.wait_push(push).await; + let _ = rx.wait_pull().await; // Discard the result of the write action } - self.restore_after_search(&shift_cfg); + self.restore_after_search(); state.last_discrepancy = last_zero; state.finished = last_zero == 0; @@ -236,44 +230,42 @@ impl<'d, PIO: Instance, const SM: usize> PioOneWire<'d, PIO, SM> { Some(value) } - fn prepare_search(&mut self) -> ShiftConfig { - let shift_cfg = self.cfg.shift_in; - self.cfg.shift_in = ShiftConfig { - auto_fill: true, - direction: ShiftDirection::Left, - threshold: 2, - }; - self.cfg.shift_out = ShiftConfig { - auto_fill: true, - direction: ShiftDirection::Right, - threshold: 1, - }; + fn prepare_search(&mut self) { + self.cfg.shift_in.threshold = 1; + self.cfg.shift_in.direction = ShiftDirection::Left; + self.cfg.shift_out.threshold = 1; self.sm.set_enable(false); self.sm.set_config(&self.cfg); - unsafe { - self.sm.exec_jmp(self.search_addr); - } - self.sm.set_enable(true); - shift_cfg - } - - fn restore_after_search(&mut self, cfg: &ShiftConfig) { - self.cfg.shift_in = *cfg; - self.cfg.shift_out = *cfg; - - self.sm.set_enable(false); - self.sm.set_config(&self.cfg); + // set_config jumps to the wrong address so jump to the right one here unsafe { self.sm.exec_jmp(self.next_bit_addr); } + self.sm.set_enable(true); + } + + fn restore_after_search(&mut self) { + self.cfg.shift_in.threshold = 8; + self.cfg.shift_in.direction = ShiftDirection::Right; + self.cfg.shift_out.threshold = 8; + + self.sm.set_enable(false); + self.sm.set_config(&self.cfg); + + // Clear the state in case we aborted prematurely with some bits still in the shift registers self.sm.clear_fifos(); self.sm.restart(); + + // set_config jumps to the wrong address so jump to the right one here + unsafe { + self.sm.exec_jmp(self.next_bit_addr); + } self.sm.set_enable(true); } } +/// Onewire search state pub struct PioOneWireSearch { last_rom: u64, last_discrepancy: u8, @@ -281,6 +273,7 @@ pub struct PioOneWireSearch { } impl PioOneWireSearch { + /// Create a new Onewire search state pub fn new() -> Self { Self { last_rom: 0, @@ -289,6 +282,7 @@ impl PioOneWireSearch { } } + /// Search for the next address on the bus pub async fn next(&mut self, pio: &mut PioOneWire<'_, PIO, SM>) -> Option { if self.finished { None @@ -297,6 +291,7 @@ impl PioOneWireSearch { } } + /// Is finished when all devices have been found pub fn is_finished(&self) -> bool { self.finished }