humpback-dds/src/flash.rs

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Rust
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use embedded_hal::{
digital::v2::{OutputPin, InputPin},
blocking::spi::Transfer,
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blocking::delay::DelayUs,
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};
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#[derive(Debug)]
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pub enum FPGAFlashError {
SPICommunicationError,
NegotiationError,
ResetStatusError,
}
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const DATA: &'static [u8] = include_bytes!("../build/top.bin");
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// A public method to flash iCE40 FPGA on Humpback
pub fn flash_ice40_fpga<SPI: Transfer<u8>,
SS: OutputPin,
RST: OutputPin,
DELAY: DelayUs<u32>,
DONE: InputPin>
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(mut spi: SPI, mut ss: SS, mut creset: RST, cdone: DONE, mut delay: DELAY) -> Result<(), FPGAFlashError>
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{
// Data buffer setup
let mut dummy_byte :[u8; 1] = [0x00];
let mut dummy_13_bytes :[u8; 13] = [0x00; 13];
// Drive CRESET_B low
creset.set_low()
.map_err(|_| FPGAFlashError::NegotiationError)?;
// Drive SPI_SS_B low
ss.set_low()
.map_err(|_| FPGAFlashError::NegotiationError)?;
// Wait at least 200ns
delay.delay_us(1_u32);
// Drive CRESET_B high
creset.set_high()
.map_err(|_| FPGAFlashError::NegotiationError)?;
// Wait at least another 1200us to clear internal config memory
delay.delay_us(1200_u32);
// Before data transmission starts, check if C_DONE is truly low
// If C_DONE is high, the FPGA reset procedure is unsuccessful
match cdone.is_low() {
Ok(true) => {},
_ => return Err(FPGAFlashError::ResetStatusError),
};
// Set SPI_SS_B high
ss.set_high()
.map_err(|_| FPGAFlashError::NegotiationError)?;
// Send 8 dummy clock, effectively 1 byte of 0x00
spi.transfer(&mut dummy_byte)
.map_err(|_| FPGAFlashError::SPICommunicationError)?;
// Drive SPI_SS_B low
ss.set_low()
.map_err(|_| FPGAFlashError::NegotiationError)?;
// Send the whole image without interruption
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for byte in DATA.into_iter() {
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let mut single_byte_slice = [*byte];
spi.transfer(&mut single_byte_slice)
.map_err(|_| FPGAFlashError::SPICommunicationError)?;
}
// Drive SPI_SS_B high
ss.set_high()
.map_err(|_| FPGAFlashError::NegotiationError)?;
// Send at another 100 dummy clocks (choosing 13 bytes)
spi.transfer(&mut dummy_13_bytes)
.map_err(|_| FPGAFlashError::SPICommunicationError)?;
// Check the CDONE output from FPGA
// CDONE needs to be high
match cdone.is_high() {
Ok(true) => {},
_ => return Err(FPGAFlashError::ResetStatusError),
};
// Send at least another 49 clock cycles to activate IO pins (choosing same 13 bytes)
spi.transfer(&mut dummy_13_bytes).map_err(|_| FPGAFlashError::SPICommunicationError)?;
Ok(())
}