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#include <array>
#include <cstdint>
namespace
{
constexpr std::uint32_t base_address = 0x4004'c000u;
std::uint32_t volatile * const control_status_addr = reinterpret_cast<std::uint32_t*>(base_address + 0x0u);
std::uint32_t volatile * const result_addr = reinterpret_cast<std::uint32_t*>(base_address + 0x4u);
void
select_input(std::uint32_t index)
{
constexpr std::uint32_t ainsel = 0x111u;
*control_status_addr = (*control_status_addr & ~(ainsel << 12)) | ((index & ainsel) << 12);
}
bool
ready()
{
return (*control_status_addr & 1u << 8) != 0u;
}
bool
error()
{
return (*control_status_addr & 1u << 9) != 0u;
}
void
start_once()
{
*control_status_addr |= (1u << 2);
}
void
enable(bool en)
{
*control_status_addr |= en ? (1u << 2) : 0u;
}
std::uint32_t
result()
{
return *result_addr & 0x0000'0fffu;
}
std::array<std::uint32_t, 2> previous_samples { 0xffff'ffffu, 0xffff'ffffu };
}
namespace adc
{
struct Sample
{
std::uint8_t value {0};
bool changed {false};
};
void
init()
{
enable(true);
}
std::array<Sample, 2>
get_samples()
{
while (!ready());
std::array<Sample, 2> samples {};
for (std::size_t i = 0; i < samples.size(); i++)
{
select_input(i);
start_once();
while (!ready());
std::uint32_t const measurement = result();
samples[i].changed = measurement != previous_samples[i];
previous_samples[i] = measurement;
samples[i].value = measurement * 127u / 4095u; // TODO add hysteresis
}
return samples;
}
}
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