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firmware: fix order of bits clocked into hmc542. 

Fixes #993.
This commit is contained in:
whitequark 2018-05-05 03:12:13 +00:00
parent 917a4185eb
commit c646409dbe
1 changed files with 9 additions and 7 deletions
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16
artiq/firmware/libboard_artiq/hmc542.rs
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@ -25,27 +25,29 @@ fn set_pins(card_index: usize, chan_index: usize, pins: u32) {
pub fn program(card_index: usize, chan_index: usize, atten: u8) {
assert!(card_index < 4 && chan_index < 2);
// 0b111111 = 1dB
info!("card {} channel {} set to {}{} dB",
card_index, chan_index,
atten / 2, if atten % 2 != 0 { ".5" } else { "" });
// 0b111111 = 0dB
// 0b111110 = 0.5dB
// 0b111101 = 1dB
// 0b111100 = 1.5dB
// ...
// 0b011111 = 16dB
// ...
// 0b000000 = 31.5dB
let atten = !(atten << 2);
let atten = !atten << 2;
let set_pins = |pins| set_pins(card_index, chan_index, pins);
set_pins(PIN_RST);
set_pins(0);
for n in 0..8 {
for n in (0..8).rev() {
let sin = if atten & 1 << n != 0 { PIN_SIN } else { 0 };
set_pins(sin);
set_pins(sin | PIN_CLK);
}
set_pins(PIN_LE);
info!("card {} channel {} set to {}{} dB",
card_index, chan_index,
atten / 2, if atten % 2 != 0 { ".5" } else { "" });
}
/// See `program`.