Read data is 0XF4,0X53,0XFE, how to parse?
[edited by: ljln119 at 3:25 AM (GMT 0) on 14 Jan 2020]
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Looking at the timing diagram of Figure 3a, I think there could be something wrong with your communication with the ADC. The first two bits should always be zeros. Can you provide an oscilloscope photo…
When B0 is sent, the received data is hexadecimal 88,40, F0.Actual channel B0= 0.260v.When sending B1, the received data is hexadecimal E8,A7,FC, and the actual channel B1=2.495V.The Numbers don't match…
Looking at the timing diagram of Figure 3a, I think there could be something wrong with your communication with the ADC. The first two bits should always be zeros. Can you provide an oscilloscope photo showing CSL, SCK, SDI and SDO? A schematic of your circuit would also be helpful.
If you look at Table 1 of the data sheet you will see that if the first 4 bits of the output word are 0s, that indicates that the input voltage is below -Full Scale (-0.5*Vref). Let me pick a value that is not railed for an example. 20111111 hexadecimal. According to Table 1, if the first 4 bits are a Hex 2 (0010) then Vin is between 0V and 0.5*Vref. Bits 28 to 5 are the 24-bit conversion result MSB first. Bits 4 to 0 are sub LSBs that can be included if desired or ignored. For simplicity I will ignore the sub LSBs. This results in a 24-bit output code of 008888 hex. Converting that to decimal produces 34952. Dividing that by 2^24 yields 0.0020833015. Multiplying that by the reference voltage (5V) will produce the input voltage, in this case 0.0104165077V.
Thank you for your reply!Another question is, how to convert the GPIO voltage read by ltc6811-2 chip to the actual voltage value?
VREF2 Is the 34-pin output voltage of ltc6811-2。T1~T5 is connected to the MCU, JT1 is the connector, connected to the temperature probe, measuring temperature range is -55~100℃，Refer to the development board circuit。
Waiting for your reply, thank you！