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11bit ADC data from SAMD51 (M4) boards

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#11,391 4 comentarios 0 reacciones 0 asignados Ver en GitHub

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Evaluación

Dificultad
4/5
Tiempo estimado
3-5 días
Aptitud para principiantes
42/100
Tipo de issue
Error
Claridad
Bastante claro
Estado de actividad
Activo
Stack tecnológico
c
Área
embedded-iot

Línea de trabajo

Start by tracing how AnalogIn reads the ADC on SAMD51 boards and how that reading is scaled to CircuitPython’s 0–65535 range; compare this with a board where the reported values are not all even. The issue names no source files or tests, so locate the SAMD51 ADC implementation and relevant tests first. Done means explaining or fixing the even-valued 12-bit readings and verifying the behavior on the Feather M4 Express.

Escrito por el modelo de indexación a partir del texto del issue.

Descripción

analogio atmel-samd documentation
CircuitPython version and board name
`10.2.1` on Adafruit Feather M4 Express
Code/REPL
My code is too complex but the essence is `value` from `AnalogIn` (on `A5`) shifted by 4 bits.
Behavior

The values when converted from CircuitPython's 0-65535 using >> 4 to 0-4095 (12bit) values are all even.

Description

From my recent ADC testing which I was reviewing I am only seeing even values from an M4 board's ADC in CircuitPython when it's shifted to a 12 bit value. This suggests it's either set to 11 bits or something is zeroing the lsb??

Additional information

This is some of my raw data.

1311612915047,"triangle","B",0,"C","max",0,"[-1]",-0.0001875,"[8,8,6,8,6,4,8,8,6,6,6,6,6,6,6,6,6,6,8,6,6,6,6,6,6,8,8,6,8,6,6,8,8,6,6,6,6,6,6,6]"
1311659362795,"triangle","B",0,"C","max",0,"[-1]",-0.0001875,"[6,6,6,6,6,6,6,4,6,6,6,6,6,8,6,6,6,6,6,6,6,8,6,6,10,6,8,6,8,6,8,6,6,6,8,6,6,6,6,6]"
1311688812260,"triangle","B",0,"C","max",0,"[-1]",-0.0001875,"[8,8,8,6,6,6,6,6,6,8,6,6,12,6,6,6,6,6,6,6,6,6,6,6,6,6,6,8,6,6,8,6,6,6,6,8,6,8,6,6]"
1311718200689,"triangle","B",0,"C","max",0,"[-1]",-0.0001875,"[8,6,6,6,6,8,6,8,6,6,6,6,6,6,6,6,6,8,6,6,6,6,6,6,8,6,6,8,8,6,8,8,6,6,8,6,6,6,6,6]"
1311747283938,"triangle","B",0,"C","max",0,"[-1]",-0.0001875,"[8,8,6,6,6,6,6,6,6,8,6,6,8,6,6,6,6,6,4,6,6,6,6,6,8,6,6,6,6,6,14,6,6,8,6,6,6,6,4,6]"
1311785400394,"triangle","B",0,"C","max",0,"[0]",0.001125,"[6,8,8,6,8,6,6,6,6,6,6,8,6,6,6,6,6,8,6,8,6,6,6,6,6,6,6,8,6,8,6,6,6,6,8,8,6,6,6,8]"
1311832366948,"triangle","B",0,"C","max",0,"[1]",0.0024375,"[10,8,8,8,10,8,10,8,8,10,8,8,8,8,6,6,8,8,8,8,8,8,10,10,8,8,10,12,10,6,8,8,8,8,0,8,8,10,6,8]"
1311864807136,"triangle","B",0,"C","max",0,"[2]",0.00375,"[10,10,10,10,8,10,10,10,10,10,8,10,10,10,10,12,10,10,10,10,10,10,10,10,12,8,8,10,10,10,10,10,10,10,10,10,10,10,10,10]"
1311904510501,"triangle","B",0,"C","max",0,"[3]",0.004875,"[12,12,12,12,12,12,10,12,12,12,12,12,12,12,10,12,14,12,10,12,12,12,12,10,12,12,12,12,12,12,12,12,10,12,10,12,12,12,12,10]"
1311944824225,"triangle","B",0,"C","max",0,"[4]",0.006374998,"[14,12,14,12,14,12,12,12,12,14,12,12,12,12,14,14,12,14,12,14,12,12,12,14,14,12,14,14,12,14,14,16,14,14,14,14,14,12,14,12]"
1311985290540,"triangle","B",0,"C","max",0,"[5]",0.0075,"[16,14,14,16,16,16,14,14,14,20,14,14,14,14,16,16,14,10,14,14,14,14,14,16,16,14,14,16,14,14,14,16,16,16,14,14,16,14,14,14]"
1312028137218,"triangle","B",0,"C","max",0,"[6]",0.0088125,"[18,16,16,16,16,18,16,16,16,16,16,16,16,16,16,16,16,16,16,18,16,16,16,16,16,16,16,18,20,18,16,16,14,16,16,16,16,22,16,16]"
1312068511965,"triangle","B",0,"C","max",0,"[7]",0.0103125,"[18,18,18,18,18,18,18,20,18,18,18,18,18,18,18,18,18,18,18,18,18,18,18,18,18,18,18,18,18,18,18,20,18,18,18,16,18,18,14,18]"
1312108795171,"triangle","B",0,"C","max",0,"[8]",0.011625,"[24,20,20,20,18,22,20,20,18,20,20,20,20,20,20,20,20,20,20,18,20,20,20,20,20,20,20,18,20,20,20,20,20,20,20,20,20,22,20,20]"

Note the values in the last field are all even. I have same code running on many other boards and have witnessed no other problems. I am still reviewing my results so there's a small possibility this is an application bug authored by me...

Lenguaje dominante
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Forks
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