P83C266BDR datasheet(71/92 Pages) PHILIPS

71 / 92 page

1999 Mar 10

Philips Semiconductors

Product speciﬁcation

Microcontrollers for PAL/SECAM TV

with OSD and VST

P8xCx66 family

18.2

EPROM Programming mode

In the EPROM programming mode the selected EPROM is

under the direct control of the external pins. For entering

the programming mode the RESET pin serves as the data

input and the XTALIN pin serves as the clock input. There

is no need to synchronise the addresses, data, read and

write signals with the CPU.

To enter the programming mode, the microcontroller must

first be reset in accordance to the normal reset procedure

to avoid the Idle mode. The programming code is then

shifted in serially via the RESET pin and stored in a

generated.

18.2.1

SERIAL PROGRAMMING CODES

Once the device has been reset the programming code

can be shifted in via the RESET pin. The 10-bit

programming code is shown in Fig.45 and defined in

Table 85.

Table 85 Programming code format

BIT

FUNCTION

9to6

Stop bits. These are the last 4 bits to be

shifted in and always take the value ‘0101’,

indicating the end of the test mode code.

5to1

Mode bits. These 5 bits follow the start bit

and select the test mode; see Table 86.

Start bit. This is the first bit to be shifted in

and is always a logic 0, indicating that the

following 5 bits are test mode code.

Fig.45 Serial programming code.

handbook, halfpage

MGM683

bit 0

XXXXX

0 1 0

bit 9

Stop bits

Mode bits

Start bit

Table 86 Test mode selection.

18.2.2

ENTERING THE PROGRAMMING MODE

The procedure for entering the Programming mode is

detailed below and illustrated in Fig.47

1. The normal reset should be active for at least

24 XTALIN clocks:

a) The first 10 XTALIN clocks cancel any special

modes

b) The 24 XTALIN clocks (2 machine cycles) ensure

that the CPU core is reset.

2. Shift in the programming code via the RESET pin

3. Wait at least 2 XTALIN clocks until the control signals

are ready, then the EPROM address, data and control

signals can be applied. The RESET pin should be

released within 10 XTALIN clocks to prevent the circuit

escaping from EPROM programming mode.

18.2.3

LEAVING THE PROGRAMMING MODE

The device will exit the Programming mode when the

RESET pin is driven HIGH for at least 10 XTALIN clock

cycles.

18.3

Programming and veriﬁcation

It is not recommended to carry out programming/verify

operations on a byte basis. It is far better to program all

program EPROM (or OSD EPROM) and then verify the

contents.

18.4

OSD EPROM bit map and the sequence of

programming OSDL and OSDH

Each character bit pattern is stored in the on-chip

ROM/EPROM. The character displayed on the screen is in

a 12

× 18 dot matrix format, however it is stored in the

on-chip character ROM in a 12

× 19 format. For the OSD

EPROM character the dot matrix is 16

× 19, but only

× 19 is used, therefore the high nibble of OSDH must

be filled with FH.

MODE BITS

TEST MODE

54321

00100

Program EPROM

00110

OSD EPROM

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