*note by 1net: Please take the above description with a grain of salt as it is NOT for 7004. In upd7004, we have only 2 registers: 4000 and 4001. The upd7004 has only 10bit mode, but since the code only reads 4001, the resolution is effectively 8bit... the 2lsb are discarded and not read.

• the external interrupt 1 routine jumpes to 006Ch, where it reads the value from 4001h (A/D low byte).

• the external interrupt 1 routine jumpes to 0064h, where it reads the value from 4001h (A/D HIGH byte).

hope this helps, daniel

channel mapping (including MUX):

Documentation on it was very hard to find. :)

Documentation on it was very hard to find. :) We looked and googled for months, and then finally I emailed NEC and they got back to me within 10 hours!!! Talk about customer service! Download the uPD7004C.PDF datasheet

This PDF talks about the UPD7004C on page 31-35. George found this PDF on a NEC ADC that is only 4 channel, but of the same family.

I emailed NEC and they got back to me within 10 hours!!! Talk about customer service! Download the uPD7004C datasheet here

l3st4rd says:

l3st4rd says:

Note to self: need to determine whether chip is being used in serial or parallel mode and make appropriate changes to the following table. Highly suspect parallel mode.

Note to self: chip is used exclusively in parallel mode. Make appropriate changes to the following table.

Further note: Channel 7 is multiplexed using a Toshiba 8 channel analog MUX. 15 channels total A/D capability in ECU.

|function|short|pin|uPD7004C|pin|short|function |Channel 4|CH4|1|uPD7004C|28|CH3|Channel 3 |Channel 5|CH5|2|uPD7004C|27|CH2|Channel 2 |Channel 6|CH4|3|uPD7004C|26|CH3|Channel 1 |Channel 7|CH5|4|uPD7004C|25|CH2|Channel 0 |Reference Voltage|VREF|5|uPD7004C|24|A.GND|Analog Ground |Digital GND|D.GND|6|uPD7004C|23|A.VDD|Analog supply | |DB7/SO|7|uPD7004C|22|_CS|Chip select

%META:FILEATTACHMENT{name="uPD7004C.PDF" attr="" comment="Datasheet for UPD 7004C" date="1078511865" path="C:\Documents and Settings\Administrator\Desktop\temp\wiki\uPD7004C.PDF" size="556339" user="blundar" version="1.1"}%

%META:TOPICINFO{author="blundar" date="1077237440" format="1.0" version="1.1"}% The NEC UPD7004C is an ADC chip found in OBD0 MPFI ECUs.

Documentation on it was very hard to find. :)

This PDF talks about the UPD7004C on page 31-35. George found this PDF on a NEC ADC that is only 4 channel, but of the same family.

I emailed NEC and they got back to me within 10 hours!!! Talk about customer service! Download the uPD7004C datasheet here

l3st4rd says: i got a description of the uPD7002. it has 3 internal registers(here 4000, 4001, 4002):

• 4000h is the control register
• 4001 and 4002 are the data registers.

a measure is started by sending one byte to the control register. it can operate in 8 and 12 bit mode. the control bits are:

• bit 0: } control bits for channel multiplexer
• bit 1: } 00 = channel 0, 01 = channel 1, 10 = channel 3...
• bit 2: no function (or possilby 3rd channel ctrl bit for 7004?)
• bit 3: 1 = 12bit mode, 0 = 8bit mode
• bit 4 to 7: no function

In practice, use of the chip is somewhat like what follows:

• the external interrupt 1 routine jumpes to 006Ch, where it reads the value from 4001h (A/D low byte).
• then it resets the A/D low byte by writing 0 to 4001h
• then it starts the next 8bit measure by sending 0 - 7 to 4000h(control register).
• the first seven times it takes the values from channel 0 to 6 and stores them at external ram 0000h - 0006h. *the next 8 times, it's called, it takes the value from channel 7 and stores it at external ram 0007h - 000Eh (this all assuming that internal mem 07Dh is a counter from 0 to 0Eh)

hope this helps, daniel

Now that we have the datasheet, this can more definitively be settled.

Note to self: need to determine whether chip is being used in serial or parallel mode and make appropriate changes to the following table. Highly suspect parallel mode.

|function|short|pin|uPD7004C|pin|short|function |Channel 4|CH4|1|uPD7004C|28|CH3|Channel 3 |Channel 5|CH5|2|uPD7004C|27|CH2|Channel 2 |Channel 6|CH4|3|uPD7004C|26|CH3|Channel 1 |Channel 7|CH5|4|uPD7004C|25|CH2|Channel 0 |Reference Voltage|VREF|5|uPD7004C|24|A.GND|Analog Ground |Digital GND|D.GND|6|uPD7004C|23|A.VDD|Analog supply | |DB7/SO|7|uPD7004C|22|_CS|Chip select