forked from M-Labs/artiq-zynq
150 lines
4.4 KiB
Rust
150 lines
4.4 KiB
Rust
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use crate::i2c;
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use log::info;
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// Only the bare minimum registers. Bits/IO connections equivalent between IC types.
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struct Registers {
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// PCA9539 equivalent register names in comments
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iodira: u8, // Configuration Port 0
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iodirb: u8, // Configuration Port 1
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gpioa: u8, // Output Port 0
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gpiob: u8, // Output Port 1
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}
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pub struct IoExpander {
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busno: i32,
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port: u8,
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address: i32,
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iodir: [u8; 2],
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out_current: [u8; 2],
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out_target: [u8; 2],
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registers: Registers,
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}
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impl IoExpander {
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pub fn new(index: u8) -> Result<Self, &'static str> {
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// Both expanders on SHARED I2C bus
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let mut io_expander = match index {
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0 => IoExpander {
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busno: 0,
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port: 11,
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address: 0x40,
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iodir: [0xff; 2],
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out_current: [0; 2],
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out_target: [0; 2],
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registers: Registers {
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iodira: 0x00,
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iodirb: 0x01,
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gpioa: 0x12,
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gpiob: 0x13,
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},
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},
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1 => IoExpander {
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busno: 0,
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port: 11,
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address: 0x42,
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iodir: [0xff; 2],
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out_current: [0; 2],
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out_target: [0; 2],
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registers: Registers {
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iodira: 0x00,
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iodirb: 0x01,
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gpioa: 0x12,
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gpiob: 0x13,
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},
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},
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_ => return Err("incorrect I/O expander index"),
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};
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if !io_expander.check_ack()? {
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info!(
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"MCP23017 io expander {} not found. Checking for PCA9539.",
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index
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);
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io_expander.address += 0xa8; // translate to PCA9539 addresses (see schematic)
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io_expander.registers = Registers {
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iodira: 0x06,
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iodirb: 0x07,
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gpioa: 0x02,
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gpiob: 0x03,
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};
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if !io_expander.check_ack()? {
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return Err("Neither MCP23017 nor PCA9539 io expander found.");
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};
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}
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Ok(io_expander)
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}
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fn select(&self) -> Result<(), &'static str> {
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let mask: u16 = 1 << self.port;
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i2c::switch_select(self.busno, 0x70, mask as u8 as i32);
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i2c::switch_select(self.busno, 0x71, (mask >> 8) as u8 as i32);
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Ok(())
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}
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fn write(&self, addr: u8, value: u8) -> Result<(), &'static str> {
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i2c::start(self.busno);
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i2c::write(self.busno, self.address as i32);
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i2c::write(self.busno, addr as i32);
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i2c::write(self.busno, value as i32);
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i2c::stop(self.busno);
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Ok(())
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}
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fn check_ack(&self) -> Result<bool, &'static str> {
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// Check for ack from io expander
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self.select()?;
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i2c::start(self.busno);
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let ack = i2c::write(self.busno, self.address);
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i2c::stop(self.busno);
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Ok(ack)
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}
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fn update_iodir(&self) -> Result<(), &'static str> {
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self.write(self.registers.iodira, self.iodir[0])?;
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self.write(self.registers.iodirb, self.iodir[1])?;
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Ok(())
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}
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pub fn init(&mut self) -> Result<(), &'static str> {
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self.select()?;
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self.update_iodir()?;
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self.out_current[0] = 0x00;
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self.write(self.registers.gpioa, 0x00)?;
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self.out_current[1] = 0x00;
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self.write(self.registers.gpiob, 0x00)?;
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Ok(())
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}
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pub fn set_oe(&mut self, port: u8, outputs: u8) -> Result<(), &'static str> {
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self.iodir[port as usize] &= !outputs;
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self.update_iodir()?;
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Ok(())
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}
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pub fn set(&mut self, port: u8, bit: u8, high: bool) {
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if high {
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self.out_target[port as usize] |= 1 << bit;
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} else {
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self.out_target[port as usize] &= !(1 << bit);
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}
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}
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pub fn service(&mut self) -> Result<(), &'static str> {
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if self.out_target != self.out_current {
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self.select()?;
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if self.out_target[0] != self.out_current[0] {
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self.write(self.registers.gpioa, self.out_target[0])?;
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self.out_current[0] = self.out_target[0];
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}
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if self.out_target[1] != self.out_current[1] {
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self.write(self.registers.gpiob, self.out_target[1])?;
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self.out_current[1] = self.out_target[1];
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}
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}
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Ok(())
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}
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}
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