[参考译文] EVM430-FR6043：避免 USS_initAlgorithms ()后续引导延迟、在 FRAM 中缓存配置数据

尊敬的 Cash Hao：

感谢您的意见。 我现在成功地使用以下代码进行了一个有效的设置：

/*
 * A replacement for USS_initAlgorithms() that only runs the
 * full initialization during the first boot and then caches
 * the results in FRAM for faster subsequent boots.
 *
 * NOTE: The internal workings of the USS library are not
 * really documented and it needed some reverse engineering
 * to get this to work:
 * 1. Take full memory dump before USS_initAlgorithms()
 * 2. Take full memory dump after USS_initAlgorithms()
 * 3. Find differing data
 * 4. Use linker map file to find out to which symbols the
 *    differences belong.
 * 5. Use `nm -S USS_SW_CCS_large_code_large_data.lib` to find
 *    the size of each of these symbols.
 * For this reason, the implementation is rather fragile and
 * may fail if USS parameters are changed, as these may cause
 * other symbols to become relevant.
 *
 * See also: 
 * e2e.ti.com/.../
 */
extern void USS_lea_init(void);
extern void *gFilterConstant;
extern void *gHilbertFilterConstant;
extern void *gUSSAlgObject;
typedef struct uss_init_buffer_ {
    uint8_t gFilterConstant[0x28];
    uint8_t gHilbertFilterConstant[0x18];
    uint8_t gUSSAlgObject[0x116];
} uss_init_buffer_t;
#pragma PERSISTENT(persist_uss_init_buffer)
static uss_init_buffer_t persist_uss_init_buffer = {0};
static void uss_init_quick(void) {
    if (gUssSWConfig.validationKey != CONFIG_VALIDATION_KEY) {
        USS_initAlgorithms(&gUssSWConfig);
        /* Store initialized data to nonvolatile memory (FRAM). */
        memcpy(persist_uss_init_buffer.gFilterConstant, &gFilterConstant, sizeof(persist_uss_init_buffer.gFilterConstant));
        memcpy(persist_uss_init_buffer.gHilbertFilterConstant, &gHilbertFilterConstant, sizeof(persist_uss_init_buffer.gHilbertFilterConstant));
        memcpy(persist_uss_init_buffer.gUSSAlgObject, &gUSSAlgObject, sizeof(persist_uss_init_buffer.gUSSAlgObject));
        /* Take the shortcut on next boot. */
        gUssSWConfig.validationKey = CONFIG_VALIDATION_KEY;
    } else {
        USS_lea_init();
        /* Initialize LEA hardware, but otherwise just restore precalculated
         * data from nonvolatile memory. */
        memcpy(&gFilterConstant, persist_uss_init_buffer.gFilterConstant, sizeof(persist_uss_init_buffer.gFilterConstant));
        memcpy(&gHilbertFilterConstant, persist_uss_init_buffer.gHilbertFilterConstant, sizeof(persist_uss_init_buffer.gHilbertFilterConstant));
        memcpy(&gUSSAlgObject, persist_uss_init_buffer.gUSSAlgObject, sizeof(persist_uss_init_buffer.gUSSAlgObject));
    }
}

不幸的是,我现在才发现,我在初始分析过程中犯了一个错误。 USS_initAlgorithms()需要它的时间、但只有几个100us。 真正实质性的延迟来自 USS_configureUltrasonicMeasure()、更具体地说、来自 commonConfigureMultiTone()中发射脉冲模式的计算。 但至少"修复"这是相当容易的:由于结果存储在持久 USS 配置数据中,它足以在慢代码周围加上"if":

#if defined(__MSP430_HAS_SAPH_A__) && (USS_PULSE_MODE == USS_PULSE_MODE_MULTI_TONE)
USS_message_code commonConfigureMultiTone(USS_SW_Library_configuration *config)
{

    USS_Pulse_Multitone_Configuration* multConf;
    int32_t i,f1Freq,f2Freq,pulseCenterFreq, pulseBandwidth;
    uint32_t fSinInc, pPGFreq;
    _iq30 iq30Btemp;
    _iq23 iq23B;
    _iq18 iq18FIncrease;
    _iq12 iq12PulseDurFreq, iq12pPGCycles;
    _iq10 iq10FIncreased;
    uint16_t *pCurrArray;
    int16_t dmaCycles, xCycles,eCycles, stopAddr,pPGCycles;
    uint8_t ehperIndex, elperIndex, xhperIndex, xlperIndex,currentState;
    int8_t currentValue, previousValue;

    multConf =
            (USS_Pulse_Multitone_Configuration*) config->measurementConfig->pulseConfig->pToneConfig;

    /* The calculation of the pulse streams takes a considerable amount of
     * time (approx. 400ms), but the results are going into FRAM, and are
     * persistent anyway. So it is fine to just skip the calculation except for
     * the first boot after a firmware download. */
    if (config->validationKey != CONFIG_VALIDATION_KEY) {

        // Note: It is assumed that f1Freq<f2Freq
        f1Freq = (int32_t)config->measurementConfig->pulseConfig->F1Frequency;
        f2Freq = (int32_t)config->measurementConfig->pulseConfig->F2Frequency;

        // Calculate the excitation pulse bandwidth
        pulseBandwidth = (f2Freq -f1Freq);

        // ... more code ...
        
        }


        privatePadMultiToneConfig(config, multConf);
    }  // End of skipping for faster boots, the remaining code must stay.


 /*
  * Configure e-pulses and x-pulses RAM memory
  */

    eCycles = (multConf->numOfTrillcycles);
    xCycles = (multConf->numOfTrillcycles) -1;
    dmaCycles = eCycles + xCycles;
    stopAddr = (xCycles)*6+3;

    // ...

现在、我们的传感器在大约30ms 后开始提供数据。 仍然不是瞬间,但更合理的比半秒.

再次感谢！

祝您愉快的周末、
Philipp