MSM5832 real-time clock pinout
DIP-18. Clock and calendar for HERO 1 (U315 on the I/O board).
The HERO 1 clock. It has a 4-bit register address (A0-A3) and a 4-bit open-drain data bus (D0-D3), on a 32.768 kHz crystal. HOLD freezes the counters while the CPU reads or sets them; keep it under 1 s or the clock loses time. The HERO 1 drives the address nibbles from $C2C0 and the data through $C300. A faulty clock shows as a wrong or stopped time.
Open the interactive MSM5832 pinoutPins
| Pin | Name | Type | Signal |
|---|---|---|---|
| 1 | VDD | power | +5 V supply; keeps counting with backup down to 2.2 V. |
| 2 | WRITE | ctrl | Write enable, active high; writes when CS, HOLD and WRITE are all high. |
| 3 | READ | ctrl | Read enable, active high; reads when CS and READ are high. |
| 4 | A0 | addr | Register address bit 0. |
| 5 | A1 | addr | Register address bit 1. |
| 6 | A2 | addr | Register address bit 2. |
| 7 | A3 | addr | Register address bit 3. |
| 8 | CS | ctrl | Chip select, active high, with a raised threshold so the bus is locked out on power fail. |
| 9 | D0 | data | Data bit 0 (LSB), open drain, needs a 4.7 kohm or larger pull-up. With all address lines high it outputs 1024 Hz. |
| 10 | D1 | data | Data bit 1, open drain; 1 Hz reference output in that mode. |
| 11 | D2 | data | Data bit 2, open drain; 1/60 Hz reference output in that mode. |
| 12 | D3 | data | Data bit 3 (MSB), open drain; 1/3600 Hz reference output in that mode. |
| 13 | GND | ground | Ground. |
| 14 | TEST | ctrl | Test input; leave open or grounded. Pulses here clock the counters directly. |
| 15 | ±30 ADJ | ctrl | ±30 s correction: a high pulse of at least 31.25 ms rounds the seconds to zero. |
| 16 | XT | clock | 32.768 kHz crystal pin, or external clock input. |
| 17 | /XT | clock | Crystal pin; left open with an external clock. |
| 18 | HOLD | ctrl | Count hold, active high, internal pull-down; freezes the counters for a safe read or write (keep under 1 s). |
Fitted in
- HERO 1 U315