Hello,
i would like to use the external VAREF (VDD Pin = 5V) for reading ADC results from 5V Sensors
and (VDDP= 3,3V) for digital IO (communication with other ics and so on...
1st question: is that in principle possible? --> VDD > VDDP ?
2nd question how can i activate the external VAREF? --> I am using DAVE 4.3.2 and the ADC Measurement App 4.1.22 --> the generated code looks:
Attachment 2691
Attachment 2692
According to these pictures i thought its working without any problems.
But in my test setup goes something wrong: when i conect VDD to 5V then the VDDP Pins (normally 3,3V) rise up to 4V. When i disconect VDD, then is the reference voltage 2,5V at this pin.
Can anybody explain me what i am doing wrong?
Big Thnaks!
Andi
i would like to use the external VAREF (VDD Pin = 5V) for reading ADC results from 5V Sensors
and (VDDP= 3,3V) for digital IO (communication with other ics and so on...
1st question: is that in principle possible? --> VDD > VDDP ?
2nd question how can i activate the external VAREF? --> I am using DAVE 4.3.2 and the ADC Measurement App 4.1.22 --> the generated code looks:
Code:
/*********************** C3 Configurations ************************************/
/*C3 ADC Channel configuration structure*/
XMC_VADC_CHANNEL_CONFIG_t C3_ch_config =
{
.input_class = (uint32_t) XMC_VADC_CHANNEL_CONV_GLOBAL_CLASS0, /* Global ICLASS 0 selected */
.lower_boundary_select = (uint32_t) XMC_VADC_CHANNEL_BOUNDARY_GROUP_BOUND0,
.upper_boundary_select = (uint32_t) XMC_VADC_CHANNEL_BOUNDARY_GROUP_BOUND0,
.event_gen_criteria = (uint32_t) XMC_VADC_CHANNEL_EVGEN_NEVER, /*Channel Event disabled */
.sync_conversion = (uint32_t) 0, /* Sync feature disabled*/
.alternate_reference = (uint32_t) XMC_VADC_CHANNEL_REF_INTREF, /* Internal reference selected */ //----------------------------------------------this line to external ref ?!
.result_reg_number = (uint32_t) 13, /* GxRES[13] selected */
.use_global_result = (uint32_t) 0, /* Use Group result register*/
.result_alignment = (uint32_t) XMC_VADC_RESULT_ALIGN_RIGHT, /* Result alignment - Right Aligned*/
.broken_wire_detect_channel = (uint32_t) XMC_VADC_CHANNEL_BWDCH_VAGND, /* No Broken wire mode select*/
.broken_wire_detect = (uint32_t) 0, /* No Broken wire detection*/
.bfl = (uint32_t) 0, /* No Boundary flag */
.channel_priority = (uint32_t) 0, /* Lowest Priority 0 selected*/
.alias_channel = (int8_t) -1, /* ALIAS is Disabled*/
};
/*C3 Result configuration structure*/
XMC_VADC_RESULT_CONFIG_t C3_res_config =
{
.data_reduction_control = (uint8_t) 0, /* No Accumulation */
.post_processing_mode = (uint32_t) XMC_VADC_DMM_REDUCTION_MODE,
.wait_for_read_mode = (uint32_t) 0, /* Disabled */
.part_of_fifo = (uint32_t) 0 , /* No FIFO */
.event_gen_enable = (uint32_t) 0 /* Disable Result event */
};
/* C3 ADC channel Handle */
ADC_MEASUREMENT_CHANNEL_t ADC_MEASUREMENT_C3_handle =
{
.ch_num = (uint8_t) 2,
.group_handle = (VADC_G_TypeDef*)(void*) VADC_G1,
.group_index = (uint8_t) 1,
.ch_handle = (XMC_VADC_CHANNEL_CONFIG_t*) &C3_ch_config,
.res_handle = (XMC_VADC_RESULT_CONFIG_t*) &C3_res_config,
};Attachment 2692
According to these pictures i thought its working without any problems.
But in my test setup goes something wrong: when i conect VDD to 5V then the VDDP Pins (normally 3,3V) rise up to 4V. When i disconect VDD, then is the reference voltage 2,5V at this pin.
Can anybody explain me what i am doing wrong?
Big Thnaks!
Andi