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beckus / qemu_stm32

QEMU with an STM32 microcontroller implementation
http://beckus.github.io/qemu_stm32/
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ADC conversion initialization flag issue #24

Closed jmfriedt closed 5 years ago

jmfriedt commented 5 years ago

I have failed running examples linked with libopencm3 on qemu for STM32. Namely, starting an ADC conversion with adc_start_conversion_regular(ADC1); hangs. Indeed, this function tests the ADC_CR2_SWSTART bit of ADC_CR2 to check that conversion has started. In the RM0008 user manual of the STM32F1, we are told (p.231) that Bit 22 SWSTART: Start conversion of regular channels This bit is set by software to start conversion and cleared by hardware as soon as conversion starts. It starts a conversion of a group of regular channels if SWSTART is selected as trigger event by the EXTSEL[2:0] bits. so I think it is reasonable to conclude stm32_adc_start_conv(Stm32Adc *s) of hw/arm/stm32_adc.c with s->ADC_CR2&=~ADC_CR2_SWSTART; just before timer_mod. At least this solves the libopencm3 ADC conversion initialization issue.

beckus commented 5 years ago

Thank you for suggesting this fix. This seems reasonable so I made the change in commit 5a48797.