DocID024847 Rev 2

19/26

AN4316

Charge transfer period tuning

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Figure 10. Ideal charge transfers

Figure 11. Non-ideal charge transfers

In case of an uncompleted charge, the user must increase the charge transfer period.

Depending on the product and type of acquisition, different adjustments are necessary. The

involved parameters are in the MCU PARAMETERS section of the tsl_conf_stmxxxx.h file:

•

For STM32F0, STM32F3 and STM32L0 products embedding the TSC peripheral, the

trimming is done by increasing TSLPRM_TSC_CTPH for the charge period and/or

TSLPRM_TSC_CTPL for the transfer period, and optionally TSLPRM_TSC_PGPSC to

divide the pulse generator frequency by a power of 2.

•

For STM32L1 product, the charge transfer period is set through

TSLPRM_CT_PERIOD and TSLPRM_TIMER_FREQ parameters.

For STM8L and STM8AL products, the delay is expressed in number of NOP instructions,

executed in one cycle at the CPU frequency (max 16 MHz so in 62.5 ns). Two parameters

are provided: one for the charge period TSLPRM_DELAY_CHARGE and one for the

transfer period TSLPRM_DELAY_TRANSFER.

Please refer to the product related firmware documentation for more details.