菜单
Bare-metal SPI and I2C skill for serial peripheral buses. Use when implementing master-mode transfers, register read/write protocols, or debugging bus stalls. Activates on queries about SPI bare-metal, I2C START/STOP, sensor register read, or clock phase/polarity.
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基于 SOC 职业分类
Custom allocator skill for memory allocation strategies. Use when implementing pool/slab/arena allocators, tuning jemalloc/mimalloc, writing Rust GlobalAlloc, or benchmarking allocator performance. Activates on queries about jemalloc, mimalloc, tcmalloc, arena allocator, GlobalAlloc, or fragmentation.
NUMA programming skill for multi-socket memory locality. Use when detecting NUMA topology, binding processes with numactl, using libnuma API, building NUMA-aware data structures, or measuring remote access penalties. Activates on queries about numactl, libnuma, NUMA topology, mbind, lstopo, or remote memory access.
AF_XDP skill for high-performance XDP sockets. Use when creating AF_XDP sockets, configuring UMEM and XSK rings, XDP_REDIRECT programs, copy vs zero-copy mode, or comparing with DPDK. Activates on queries about AF_XDP, xsk_umem, XDP_REDIRECT, libbpf xsk, or zero-copy XDP.
DPDK skill for userspace packet I/O. Use when initializing EAL, configuring PMD drivers, using mbuf pools and rte_ring, setting up huge pages, RSS, or testpmd validation. Activates on queries about DPDK, EAL, rte_eth_rx_burst, hugepages, PMD, or testpmd.
io_uring skill for Linux async I/O. Use when building high-performance servers with liburing, multi-shot operations, provided buffers, fixed files, zero-copy send, or tokio-uring. Activates on queries about io_uring, SQE/CQE, liburing, IORING_OP_PROVIDE_BUFFERS, or io_uring vs epoll.
Bare-metal ADC and DAC skill. Use when configuring analog sampling, DMA-driven ADC, calibration, or DAC output on MCUs. Activates on queries about ADC bare-metal, sampling time, DMA ADC, or DAC channel setup.
| name | spi-i2c-baremetal |
| description | Bare-metal SPI and I2C skill for serial peripheral buses. Use when implementing master-mode transfers, register read/write protocols, or debugging bus stalls. Activates on queries about SPI bare-metal, I2C START/STOP, sensor register read, or clock phase/polarity. |
Implement SPI and I2C master drivers for sensor and memory chips: clock configuration, phase/polarity (SPI), START/ACK sequences (I2C), and common register-oriented transaction patterns.
/* Mode 0: CPOL=0, CPHA=0 — check slave datasheet */
SPI1->CR1 = SPI_CR1_MSTR | SPI_CR1_SSM | SPI_CR1_SSI
| (3 << SPI_CR1_BR_Pos); /* baud divider */
SPI1->CR1 |= SPI_CR1_SPE;
uint8_t spi_xfer(SPI_TypeDef *spi, uint8_t tx) {
while (!(spi->SR & SPI_SR_TXE))
;
*(volatile uint8_t *)&spi->DR = tx;
while (!(spi->SR & SPI_SR_RXNE))
;
return *(volatile uint8_t *)&spi->DR;
}
CS (GPIO bit-bang):
GPIO_CS_LOW();
spi_xfer(SPI1, reg | 0x80); /* read */
uint8_t val = spi_xfer(SPI1, 0xFF);
GPIO_CS_HIGH();
/* START → addr+W → reg → repeated START → addr+R → data → STOP */
bool i2c_read_reg(I2C_TypeDef *i2c, uint8_t dev7, uint8_t reg, uint8_t *out) {
if (!i2c_start(i2c)) return false;
if (!i2c_tx(i2c, (dev7 << 1) | 0)) return false;
if (!i2c_tx(i2c, reg)) return false;
if (!i2c_restart(i2c)) return false;
if (!i2c_tx(i2c, (dev7 << 1) | 1)) return false;
*out = i2c_rx(i2c, false); /* NACK last byte */
i2c_stop(i2c);
return true;
}
Poll SB, ADDR, TXE, RXNE, BTF per reference manual.
| Pattern | Bus |
|---|---|
reg + write data | I2C/SPI |
| `0x80 | reg` read (MSB set) |
| 16-bit big-endian length prefix | SPI flash |
/spi-i2c-baremetal I2C read of register 0x0F from device 0x68
| Symptom | Cause | Fix |
|---|---|---|
| I2C NACK | Wrong 7-bit addr (8-bit in datasheet) | Shift addr; check R/W bit |
| SPI garbage | CPOL/CPHA mismatch | Match slave mode table |
| Bus stuck SCL low | Slave clock stretch / fault | Bus recovery (clock pulses) |
| CS glitch | CS timing vs clock | Assert CS before first SCK |
skills/baremetal/gpio-baremetal — CS, SDA, SCL pinsskills/baremetal/peripherals-from-datasheet — timing requirementsskills/kernel-dev/bus-drivers-i2c-spi — Linux kernel side