PGA450Q1EVM-S: Encounter problems in the test

Hello Alan,

1. Due to the echo being masked in the blind area within the 30cm window, the PGA450-Q1 interprets this is no object, and therefore outputs the 0xFFFF result. To detect objects below 30cm, additional tuning of the ringing-decay profile is required, or the use of a separate transmitter and receiver pair on a single PGA device.

2. Since no object can be detected at 80cm, try decreasing the EEPROM based threshold. An advanced solution is to build a custom burst profile in EEPROM similar to the hard-coded short range example, but with an increase to the number of bursts (EEPROM addr 0x0B PULSE_CNTA). The custom profile can be triggered using command 5.

3. An example use case to switch between the short vs. long burst is as follows:
Initiate ultrasonic activity with a short distance measurement. If object detected, continue to loop the short distance measurement until no object is detected; else, try a long distance measurement. If an object is detected at long distance, alternate between short and long measurement bursts to ensure the object does not suddenly get very close to the sensor without being accounted for.

4. Command 6 reports the threshold values, and is decoded as follows using your return as an example:
(Note: there are seven threshold values. Command 6 identifies the range across the FIFO's 768 points where the threshold level changes. The level is an 8-bit value from 0-255.)
"09 FF 20 84 40 74 60 54 80 4C A0 3C E0 34 19 1E"

Byte1 = x09 = from FIFO 0 to 9, the threshold levelInit is Byte2 (255) (based on EEPROM addr 0x09 as initial ignore count defaulted to 9. Ignore count means threshold level is set to 255)
Byte2 = xFF = 255d level

Byte3 = x20 = from FIFO 10 to 32, the threshold level0 is Byte4 (132)
Byte4 = x84 = 132d level

Byte5 = x40 = from FIFO 33 to 64, the threshold level1 is Byte6 (116)
Byte6 = x74 = 64d level

Byte7 = x60 = from FIFO 65 to 96, the threshold level2 is Byte8 (84)
Byte8 = x54 = 84d level

Byte9 = x80 = from FIFO 97 to 128, the threshold level3 is Byte10 (76)
Byte10 = x4C = 76d level

Byte11 = xA0 = from FIFO 129 to 160, the threshold level4 is Byte12 (60)
Byte12 = x3C = 60d

Byte13 = xE0 = from FIFO 161 to 224, the threshold level5 and level6 is Byte14 (52) (in this example, level5 and level6 are the same values, lumped into a single return value, not the double interval of 224-160=64, which is twich the typical interval of 32)
Byte14 = x34 = 52d

Byte15 = x19 = from FIFO 225 to the end of the FIFO, the threshold level7 is Byte16 (30)
Byte16 = x1E = 30d