Registers Descriptions - Holtek HT67F2350 Manual

Registers Descriptions

Overall operation of the A/D converter is controlled using six registers. A read only register pair
exists to store the A/D Converter data 12-bit value. Three registers, SADC0, SADC1 and SADC2,
are the control registers which setup the operating conditions and control function of the A/D
converter. The VBGRC register contains the VBGREN bit to control the bandgap reference voltage.
Register
Name
7
SADOL
D3
(ADRFS=0)
SADOL
D7
(ADRFS=1)
S ADOH
D11
(ADRFS=0)
SADOH
—
(ADRFS=1)
SADC0 START ADBZ
SADC1 SAINS3 SAINS2
SADC2 ADPGAEN
VBGRC —
A/D Converter Data Registers – SADOL, SADOH
As these devices contain an internal 12-bit A/D converter, it requires two data registers to store the
converted value. These are a high byte register, known as SADOH, and a low byte register, known
as SADOL. After the conversion process takes place, these registers can be directly read by the
microcontroller to obtain the digitised conversion value. As only 12 bits of the 16-bit register space
is utilised, the format in which the data is stored is controlled by the ADRFS bit in the SADC0
register as shown in the accompanying table. D0~D11 are the A/D conversion result data bits.
Any unused bits will be read as zero. The A/D data registers contents will be unchanged if the A/D
converter is disabled.
ADRFS
7 6 5
0 D11 D10 D9 D8
1 0 0 0
A/D Converter Control Registers – SADC0, SADC1, SADC2
To control the function and operation of the A/D converter, three control registers known as SADC0,
SADC1 and SADC2 are provided. These 8-bit registers define functions such as the selection of
which analog signal is connected to the internal A/D converter, the digitised data format, the A/D
clock source as well as controlling the start function and monitoring the A/D converter busy status.
As these devices contain only one actual analog to digital converter hardware circuit, each of the
external and internal analog signals must be routed to the converter. The SAINS field in the SADC1
register and SACS field in the SADC0 register are used to determine which analog signal derived
from the external or internal signals will be connected to the A/D converter. The A/D converter also
contains a programmable gain amplifier, PGA, to generate the A/D converter internal reference
voltage. The overall operation of the PGA is controlled using the SADC2 register.
Rev. 1.60
Advanced A/D Flash MCU with LCD & EEPROM
6 5 4
D2 D1 D0
D6 D5 D4
D10 D9 D8
— — —
ADCEN ADRFS
SAINS1 SAINS0
— — PGAIS
— — —
A/D Converter Registers List
SADOH
4 3 2 1 0
D7 D6 D5 D4
0 D11 D10 D9 D8
A/D Converter Data Registers
168
HT67F2350/HT67F2360
HT67F2370/HT67F2390
Bit
3 2
— — —
D3 D2 D1
D7 D6 D5
D11 D10 D9
SACS3 SACS2 SACS1
— SACKS2 SACKS1
SAVRS1 SAVRS0 PGAGS1
— — —
SADOL
7 6 5 4 3
D3 D2 D1 D0 0
D7 D6 D5 D4 D3
1 0
—
D0
D4
D8
SACS0
SACKS0
PGAGS0
VBGREN
2 1 0
0 0 0
D2 D1 D0
May 16, 2019