Preliminary C8051F120/1/2/3 C8051F124/5/6/7 - KEMT FEI TUKE
Preliminary C8051F120/1/2/3 C8051F124/5/6/7 - KEMT FEI TUKE
Preliminary C8051F120/1/2/3 C8051F124/5/6/7 - KEMT FEI TUKE
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<strong>Preliminary</strong><br />
<strong>C8051F120</strong>/1/2/3<br />
<strong>C8051F124</strong>/5/6/7<br />
5. ADC0 (12-BIT ADC, <strong>C8051F120</strong>/1/4/5 ONLY)<br />
The ADC0 subsystem for the <strong>C8051F120</strong>/1/4/5 consists of a 9-channel, configurable analog multiplexer (AMUX0), a<br />
programmable gain amplifier (PGA0), and a 100 ksps, 12-bit successive-approximation-register ADC with integrated<br />
track-and-hold and Programmable Window Detector (see block diagram in Figure 5.1). The AMUX0, PGA0, Data<br />
Conversion Modes, and Window Detector are all configurable under software control via the Special Function Registers<br />
shown in Figure 5.1. The voltage reference used by ADC0 is selected as described in Section “9. VOLTAGE<br />
REFERENCE (<strong>C8051F120</strong>/2/4/6)” on page 105 for <strong>C8051F120</strong>/2/4/6 devices, or Section “10. VOLTAGE REF-<br />
ERENCE (C8051F121/3/5/7)” on page 107 for C8051F121/3/5/7 devices. The ADC0 subsystem (ADC0, trackand-hold<br />
and PGA0) is enabled only when the AD0EN bit in the ADC0 Control register (ADC0CN) is set to logic 1.<br />
The ADC0 subsystem is in low power shutdown when this bit is logic 0.<br />
Figure 5.1. 12-Bit ADC0 Functional Block Diagram<br />
ADC0GTH<br />
ADC0GTL<br />
ADC0LTH<br />
ADC0LTL<br />
24<br />
Comb.<br />
Logic<br />
AD0WINT<br />
AIN0.0<br />
AIN0.1<br />
AIN0.2<br />
AIN0.3<br />
AIN0.4<br />
AIN0.5<br />
AIN0.6<br />
AIN0.7<br />
+<br />
-<br />
+<br />
-<br />
+<br />
-<br />
+<br />
-<br />
9-to-1<br />
AMUX<br />
(SE or<br />
DIFF)<br />
X<br />
+<br />
-<br />
AD0EN<br />
AV+<br />
AGND<br />
AV+<br />
12-Bit<br />
SAR<br />
ADC<br />
SYSCLK<br />
REF<br />
12<br />
ADC0L ADC0H<br />
12<br />
TEMP<br />
SENSOR<br />
AGND<br />
AIN67IC<br />
AIN45IC<br />
AIN23IC<br />
AIN01IC<br />
AMX0CF<br />
AMX0AD3<br />
AMX0AD2<br />
AMX0AD1<br />
AMX0AD0<br />
AMX0SL<br />
AD0SC4<br />
AD0SC3<br />
AD0SC2<br />
AD0SC1<br />
AD0SC0<br />
AMP0GN2<br />
AMP0GN1<br />
AMP0GN0<br />
ADC0CF<br />
AD0CM<br />
AD0EN<br />
AD0TM<br />
AD0INT<br />
AD0BUSY<br />
AD0CM1<br />
AD0CM0<br />
AD0WINT<br />
AD0LJST<br />
ADC0CN<br />
Start Conversion<br />
00<br />
01<br />
10<br />
11<br />
AD0CM<br />
AD0BUSY (W)<br />
Timer 3 Overflow<br />
CNVSTR0<br />
Timer 2 Overflow<br />
5.1. Analog Multiplexer and PGA<br />
Eight of the AMUX channels are available for external measurements while the ninth channel is internally connected<br />
to an on-chip temperature sensor (temperature transfer function is shown in Figure 5.2). AMUX input pairs can be<br />
programmed to operate in either differential or single-ended mode. This allows the user to select the best measurement<br />
technique for each input channel, and even accommodates mode changes "on-the-fly". The AMUX defaults to<br />
all single-ended inputs upon reset. There are two registers associated with the AMUX: the Channel Selection register<br />
AMX0SL (Figure 5.6), and the Configuration register AMX0CF (Figure 5.5). The table in Figure 5.6 shows AMUX<br />
functionality by channel, for each possible configuration. The PGA amplifies the AMUX output signal by an amount<br />
determined by the states of the AMP0GN2-0 bits in the ADC0 Configuration register, ADC0CF (Figure 5.7). The<br />
PGA can be software-programmed for gains of 0.5, 2, 4, 8 or 16. Gain defaults to unity on reset.<br />
© 2002 Cygnal Integrated Products, Inc. DS008-0.8-AUG02 Page 47
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