TDA7529_11 Datasheet, PDF (16/61 Pages) STMicroelectronics – RF front-end for AM/FM DSP car-radio with IF sampling

Function description
TDA7529
3.10
GPIO - general purpose IO interface pins
The front-end has seven GPIO - general purpose control pins to switch external stages
(output), e.g amplifiers, or to read the status of external stages (input), e.g. control voltages.
Some control pins are multiplexed with other functions that are not necessary in every tuner
design (FM AGC keying, AM cascode control). All the GPIOs may put in tristate or in enable
mode. When in enable the GPIOs can be configured as shown in the following table.
All GPIOs are short-circuit protected by current limiter and voltage-tolerant up to 3.5 V.
Table 5. GPIO - general purpose IO interface pins
GPIO ports
Function
Note
GPIO1
Selects function of GPIO1: if input, connects
GPIO1 to ADC (ADC must then be configured
to use GPIO1 as input); if output, level depends
on GPIO Out Lev Ctrl → GPIO1
– AnlgIn to AD
– DigOut
GPIO2
GPIO4
GPIO5
GPIO6
GPIO7
GPIO8
Selects function of GPIO2: if input, connects
GPIO2 to ADC (ADC must then be configured
to use GPIO2 as input) and to KAGC (FM
KAGC must then be enabled); if output, level
depends on GPIO Out Lev Ctr → GPIO2
– AnlgIn to AD – Kagc In
– DigOut
Selects function of GPIO4: if input, configures _{– AnlgIn}
GPIO4 as AM Cascode V_DS input; if output,
level depends on GPIO Out Lev Ctrl → GPIO4
– DigOut
Selects function of GPIO5: if input, it is directly
connected to read-only register byte 48 bit 4; if
output, level depends on GPIO Out Lev Ctrl →
GPIO5.
When set to input, it is necessary to set IF AMP
→ GPIO5 out mode to “ON GPIO5 out En”
(labels are wrong).
Also used for production testing as analog
output (not relevant for application).
– DigIn
– Out (Dig or Anlg)
Selects function of GPIO6 if device is
configured in I²C mode: if input, it is directly
connected to read-only register byte 48 bit 5; if
output, level depends on GPIO Out Lev Ctrl →
GPIO5.
When the device is configured in SPI mode,
program GPIO Out Lev Ctr → GPIO5 to “Low”.
The value of GPIO mode → GPIO5 does not
matter
– Din (spi MISO out)
– Dout (spi MISO out)
Selects function of GPIO7: if digital output is
selected, level depends on GPIO Out Lev Ctrl
→ GPIO7; otherwise, configures GPIO7 as FM
AGC Vout
– Digital Out
– FM agc Vout
Selects function of GPIO8: if output, level
– Digital Out
depends on GPIO Out Lev Ctrl → GPIO8;
otherwise, configures GPIO8 as AM AGC Vout ^{– AM agc Vout}
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Doc ID 13311 Rev 4