'Relocation truncated to fit' error when moving adc_channel to bss section in ulp_adc_example

[maciej]

Hi,
I would like to control adc channel used in ULP program same as thresholds in ulp_adc_example.

I moved

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	/* ADC1 channel 6, GPIO34 */
	.set adc_channel, 6

to

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	.bss
	.global adc_channel
adc_channel: 
	.long 0

and use adc_channel as adc param

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	adc r1, 0, adc_channel + 1

This change introduce compile error:

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(.text+0x18): relocation truncated to fit: R_ESP32ULP_ADC_MUX against symbol `adc_channel' defined in .bss section in adc.ulp.o

Please help

[ESP_igrr]

The third argument to the ADC instruction has to be a literal value, not a pointer or a register.


adc r1, 0, adc_channel + 1 means that you are doing ADC conversion with the ADC channel number set to the address of 'adc_channel' variable, which is probably not what you want.

[maciej]

The third argument to the ADC instruction has to be a literal value, not a pointer or a register.


adc r1, 0, adc_channel + 1 means that you are doing ADC conversion with the ADC channel number set to the address of 'adc_channel' variable, which is probably not what you want.

Thank you for your reply. So can I, in some way, control in main program ADC channel used in ULP program?