SH1107 reading ID

[paulsk]

Hi, I just managed to get working a micropython project for the following hardware setup:
- Pimoroni Pico Breakout Garden (BG) base with;
- a Raspberry Pi Pico;
- a Pimoroni BG RV3028 rtc (I2C);
- an Adafruit TMP117 via Qwiic to a Pimoroni BG adapter;
- a Pimoroni BG OLED 1.12in 128x128 SPI LCD (SH1107).

In the many examples and drivers for SH1106 that I have seen, there are only used command to WRITE command or data.
I did not see commands to READ, for example READ the status of a register.

In the datasheet for the SH1107, page 40, paragraph 22 (or command 22 ?) "Read ID" is described the register that contains:
a) the SH1107 BUSY bit (b7);
b) the SH1107 ON/OFF bit (b6);
c) the SH1107 ID bits (b5~b0)

The datasheed writes on c): "These bits contain the information of the chip. They output bits 000111(it means 07)."
This paragraph also describes which lines need to have a logical state HIGH or LOW:
```
+----+--------+--------------------+-------+-----------+--------------------------+
| A0 | RD (E) | WR ( R / W ) | D7 | D6 | D5 D4 D3 D2 D1 D0 |
+----+--------+-------------------+-------+------------+--------------------------+
| 0 | 0 | 1 | BUSY | ON/OFF | ID |
+----+--------+-------------------+-------+------------+--------------------------+
```

I don't know to which lines of the OLED BG board these three lines "A0", "RD" and "WR" are connected.
The 1.12in OLED SPI BG board has 7 pins: 3-6V, CS, SCK, MOSI, DC, 0 (not connected?), GND.
My guess is the following hardware connection:
A0 -> dc ;
RD -> mosi ;
WR -> cs.

In this moment, in my version of sh1107.py, to read the ID information, I created three functions:

```
def get_ID(self):
if self.id is None:
self.read_ID() # get the OLED ID
return self.id

def clr_ID(self):
self.id_buf[0] = 0
self.id = None

def read_ID(self): # See datasheet, p.40, command # 22
self.clr_ID()
self.write_cmd(GET_ID)
# read ID D5~D0
self.spi.readinto(self.id_buf) # fill self.id_buf for test read
u = struct.unpack('>B', self.id_buf, 0)[0]
self.cs(1)
print("SH1107.read_ID(): unpacked self.id_buf = 0b{:08b}".format(u),end='\n')
# self.id = (self.id_buf[0] & 0x3F) == 0x3F # set self.id
self.id = u & 0x3F

```
while in: sh1107.__init__() are defined:
GET_ID = const(0x00)
self.id_buf = bytearray(1) # 1 byte to read SH1106's data
self.id = None

From the main.py script I used the following call :
print("OLED ID: 0x{:x}".format(OLED.get_ID()),end='\n')

The datasheet of the SH1107 in the paragraph of 'read ID' states:
ID： These bits contain the information of the chip. They output bits 000111(it means 07).

However the output of my script is:
```SH1107.read_ID(): unpacked self.id_buf = 0xffffh
SH1107.read_ID(): self.id_buf = 0b11111111``` which means 15 and means that the bits BUSY and ON/OFF are (always?) On.
for the ON/OFF this is OK but for the BUSY bit not. That should go to a LOW
state at times.
and not '0b000111' which means 7.

The 'result' in the main.py script:
OLED ID: 0x3f

I was thinking that maybe I am getting wrong data because of wrong programming.

Anyone who has an idea?

[Roberthh]

Looking into the 1107 data sheet it states clearly, that read is not possible in SPI modes. You can read data in I2C mode, but the board has to be wired accordingly.

[paulsk]

Thank you for a rapid response. So, I did not read good! Excuse me for that!