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[adc] Add support for HX71708 #821

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1e44f3a
[adc] Add support for HX71708
EllaFoxo Jan 29, 2026
ae320c6
Fix config_cmd definition to accept new parameters
EllaFoxo Jan 29, 2026
03ab7da
Ruff; add note on this adc
EllaFoxo Jan 29, 2026
7803864
ruff: chop down if long
EllaFoxo Jan 29, 2026
0584f22
ruff: trailing param end
EllaFoxo Jan 29, 2026
ef6fc4f
Positional arg
EllaFoxo Jan 29, 2026
b184553
sps_bits in impl
EllaFoxo Jan 29, 2026
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44 changes: 40 additions & 4 deletions klippy/extras/hx71x.py
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Original file line number Diff line number Diff line change
Expand Up @@ -25,12 +25,13 @@ def __init__(
default_sample_rate,
gain_options,
default_gain,
sps_bits,
):
self.printer = printer = config.get_printer()
self.name = config.get_name().split()[-1]
self.last_error_count = 0
self.consecutive_fails = 0
self.sensor_type = sensor_type
self.consecutive_fails = 0
# Chip options
dout_pin_name = config.get("dout_pin")
sclk_pin_name = config.get("sclk_pin")
Expand All @@ -50,6 +51,17 @@ def __init__(
self.sps = config.getchoice(
"sample_rate", sample_rate_options, default=default_sample_rate
)
# HX71708 configures the sample rate instead of the gain/channel.
# We forward the sps bits to hx71x_read_adc so that it can read the extra bits required
if sensor_type == "hx71708":
self.gain_or_sps = 1
self.sps_bits = config.getchoice(
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@garethky garethky Feb 4, 2026 •
edited
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This feels like this is being tacked on the side. If there are going to be different configurable properties for different sensor types then we should accept that 100%. It looks like the sub types should not have that responsibility.

Some unique config logic is needed for each sensor type and then the resulting extra_bits get passed in to this class.

For the hx71708 specifically, the gain doesn't need to be read, since its not configurable.

I could argue something similar about the HX711, its SPS cant be set in software. I've already had people complain that they set the SPS but it didn't work. Maybe I need to have HX711_10 and HX711_80 as sensor types so people don't get the wrong idea.

"sample_rate", sps_bits, default=default_sample_rate
)
else:
self.gain_or_sps = 0
self.sps_bits = 0

# gain/channel choices
self.gain_channel = int(
config.getchoice("gain", gain_options, default=default_gain)
Expand All @@ -70,8 +82,15 @@ def __init__(
# Command Configuration
self.query_hx71x_cmd = None
mcu.add_config_cmd(
"config_hx71x oid=%d gain_channel=%d dout_pin=%s sclk_pin=%s"
% (self.oid, self.gain_channel, self.dout_pin, self.sclk_pin)
"config_hx71x oid=%d gain_or_sps=%d sps_bits=%d gain_channel=%d dout_pin=%s sclk_pin=%s"
% (
self.oid,
self.gain_or_sps,
self.sps_bits,
self.gain_channel,
self.dout_pin,
self.sclk_pin,
)
)
mcu.add_config_cmd(
"query_hx71x oid=%d rest_ticks=0" % (self.oid,), on_restart=True
Expand Down Expand Up @@ -179,6 +198,7 @@ def __init__(self, config):
# HX711 gain/channel options
{"A-128": 1, "B-32": 2, "A-64": 3},
"A-128",
{},
)


Expand All @@ -193,7 +213,23 @@ def __init__(self, config):
# HX717 gain/channel options
{"A-128": 1, "B-64": 2, "A-64": 3, "B-8": 4},
"A-128",
{},
)


class HX71708(HX71xBase):
def __init__(self, config):
super(HX71708, self).__init__(
config,
"hx71708",
# HX717 sps options
{320: 320, 80: 80, 20: 20, 10: 10},
320,
# HX717 gain/channel options
{"A-128": 1},
"A-128",
{320: 4, 3: 80, 20: 2, 10: 1},
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@garethky garethky Feb 4, 2026

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looks like the 80 SPS option is transposed

{320: 4, 3: 80, 20: 2, 10: 1},
{320: 4, 80: 3, 20: 2, 10: 1},

)


HX71X_SENSOR_TYPES = {"hx711": HX711, "hx717": HX717}
HX71X_SENSOR_TYPES = {"hx711": HX711, "hx717": HX717, "hx71708": HX71708}
37 changes: 26 additions & 11 deletions src/sensor_hx71x.c
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Original file line number Diff line number Diff line change
Expand Up @@ -17,6 +17,8 @@

struct hx71x_adc {
struct timer timer;
uint8_t gain_or_sps;
uint8_t sps_bits;
uint8_t gain_channel; // the gain+channel selection (1-4)
uint8_t flags;
uint32_t rest_ticks;
Expand Down Expand Up @@ -77,7 +79,7 @@ hx71x_delay(void)

// Read 'num_bits' from the sensor
static uint32_t
hx71x_raw_read(struct gpio_in dout, struct gpio_out sclk, int num_bits)
hx71x_raw_read(struct gpio_in dout, struct gpio_out sclk, uint_fast8_t num_bits)
{
uint32_t bits_read = 0;
while (num_bits--) {
Expand Down Expand Up @@ -146,8 +148,15 @@ static void
hx71x_read_adc(struct hx71x_adc *hx71x, uint8_t oid)
{
// Read from sensor
uint_fast8_t gain_channel = hx71x->gain_channel;
uint32_t adc = hx71x_raw_read(hx71x->dout, hx71x->sclk, 24 + gain_channel);
uint_fast8_t gain_or_sps = hx71x->gain_or_sps;

uint_fast8_t extra_bits;
if (gain_or_sps == 1) {
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why not just have a single argument called "extra_bits" or maybe "setting_bits" and used that throughtout. That gets rid of the gain_or_sps flag and sps_bits

Even the error check is checking the same range so it would still function correctly.

extra_bits = hx71x->sps_bits;
} else {
extra_bits = hx71x->gain_channel;
}
uint32_t adc = hx71x_raw_read(hx71x->dout, hx71x->sclk, 24u + extra_bits);

// Clear pending flag (and note if an overflow occurred)
irq_disable();
Expand All @@ -156,12 +165,12 @@ hx71x_read_adc(struct hx71x_adc *hx71x, uint8_t oid)
irq_enable();

// Extract report from raw data
uint32_t counts = adc >> gain_channel;
uint32_t counts = adc >> extra_bits;
if (counts & 0x800000)
counts |= 0xFF000000;

// Check for errors
uint_fast8_t extras_mask = (1 << gain_channel) - 1;
uint_fast8_t extras_mask = (1 << extra_bits) - 1;
if ((adc & extras_mask) != extras_mask) {
// Transfer did not complete correctly
hx71x->last_error = SAMPLE_ERROR_DESYNC;
Expand All @@ -186,17 +195,23 @@ command_config_hx71x(uint32_t *args)
struct hx71x_adc *hx71x = oid_alloc(args[0]
, command_config_hx71x, sizeof(*hx71x));
hx71x->timer.func = hx71x_event;
uint8_t gain_channel = args[1];
if (gain_channel < 1 || gain_channel > 4) {
uint8_t gain_or_sps = args[1];
uint8_t sps_bits = args[2];
uint8_t gain_channel = args[3];
if (gain_or_sps == 0 && (gain_channel < 1 || gain_channel > 4)) {
shutdown("HX71x gain/channel out of range 1-4");
}
if (gain_or_sps == 1 && (sps_bits < 1 || sps_bits > 4)) {
shutdown("HX71x sample_rate out of range 1-4");
}
hx71x->gain_or_sps = gain_or_sps;
hx71x->sps_bits = sps_bits;
hx71x->gain_channel = gain_channel;
hx71x->dout = gpio_in_setup(args[2], 1);
hx71x->sclk = gpio_out_setup(args[3], 0);
hx71x->dout = gpio_in_setup(args[4], 1);
hx71x->sclk = gpio_out_setup(args[5], 0);
gpio_out_write(hx71x->sclk, 1); // put chip in power down state
}
DECL_COMMAND(command_config_hx71x, "config_hx71x oid=%c gain_channel=%c"
" dout_pin=%u sclk_pin=%u");
DECL_COMMAND(command_config_hx71x, "config_hx71x oid=%c gain_or_sps=%c sps_bits=%c gain_channel=%c"" dout_pin=%u sclk_pin=%u");

// start/stop capturing ADC data
void
Expand Down